爱上源码，重学Spring IoC深入

1. 回答：
2. 我们为什么要学习源码？
3. 1、知其然知其所以然
4. 2、站在巨人的肩膀上，提高自己的编码水平
5. 3、应付面试

复制代码

1.1  Spring源码阅读小技巧

1、类层次藏得太深，不要一个类一个类的去看，遇到方法该进就大胆的进
2、更不要一行一行的去看，看核心点，有些方法并不重要，不要跟它纠缠
3、看不懂的先不看，根据语义和返回值能知道这个方法达到了啥目的即可
4、只看核心接口（下面标注了重点的地方）和核心代码，有些地方也许你使用spring以来都没触发过
5、debug跟步走，源码中给大家标注好了，见到 ”===>“ 就进去
​<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="userService" />
</beans><?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="userService" />
</beans>进去之前，下一行打个断点，方便快速回到岔路口
​<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="userService" />
</beans><?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="userService" />
</beans>进去之前，可以先点方法看源码，再debug跟进
6、广度优先，而非深度优先。先沿着主流程走，了解大概，再细化某些方法
7、认命。spring里多少万行的代码，一部书都写不完。只能学关键点
阅读源码目的
加深理解spring的bean加载过程
面试吹牛x
江湖传说，spring的类关系是这样的……

1.2 IoC初始化流程与继承关系

1. 引言
2. 在看源码之前需要掌握Spring的继承关系和初始化

复制代码

1)  IoC容器初始化流程

目标：
1、IoC容器初始化过程中到底都做了哪些事情（宏观目标）
2、IoC容器初始化是如何实例化Bean的（划重点，最终目标）

1. //没有Spring之前我们是这样的
2. User user=new User();
3. user.xxx();
5. //有了Spring之后我们是这样的
6. <bean id="userService" >
7. User user= context.getBean("xxx");
8. user.xxx();

复制代码

IoC流程简化图：

tips：
下面的流转记不住没有关系
在剖析源码的整个过程中，我们一直会拿着这个图和源码对照

初始化：
1、容器环境的初始化
2、Bean工厂的初始化（IoC容器启动首先会销毁旧工厂、旧Bean、创建新的工厂）
读取与定义
读取：通过BeanDefinitonReader读取我们项目中的配置（application.xml）
定义：通过解析xml文件内容，将里面的Bean解析成BeanDefinition（未实例化、未初始化）
实例化与销毁
Bean实例化、初始化（注入）
销毁缓存等
扩展点
事件与多播、后置处理器
复杂的流程关键点：

重点总结：
1、工厂初始化过程
2、解析xml到BeanDefinition，放到map
3、调用后置处理器
4、从map取出进行实例化( ctor.newInstance)
5、实例化后放到一级缓存(工厂)

2) 容器与工厂继承关系

tips：
别紧张，下面的继承记不住没有关系
关注颜色标注的几个就可以

目标：简单理解ioC容器继承关系

继承关系理解：
1、ClassPathXmlApplicationContext最终还是到了 ApplicationContext 接口，同样的，我们也可以使用绿颜色的 FileSystemXmlApplicationContext 和 AnnotationConfigApplicationContext 这两个类完成容器初始化的工作
2、FileSystemXmlApplicationContext 的构造函数需要一个 xml 配置文件在系统中的路径，其他和 ClassPathXmlApplicationContext 基本上一样
3、AnnotationConfigApplicationContext 的构造函数扫描classpath中相关注解的类，主流程一样
课程中我们以最经典的 classpathXml 为例。

Bean工厂继承关系

目标：
ApplicationContext   和  BeanFactory 啥关系？
BeanFactory 和 FactoryBean呢？

总结：
别害怕，上面的继承关系不用刻意去记住它
其实接触到的就最下面这个！
1.3 开始搭建测试项目

四步：
1、新建测试module项目
首先我们在 Spring 源码项目中新增一个测试项目，点击 New -> Module... 创建一个 Gradle 的 Java 项目

2、详细信息


3、设置gradle

4、完善信息

在 build.gradle 中添加对 Spring 源码的依赖：

1. compile(project(':spring-context'))

复制代码

spring-context 会自动将 spring-core、spring-beans、spring-aop、spring-expression 这几个基础 jar 包带进来。

接着，我们需要在项目中创建一个 bean 和配置文件（application.xml）及启动文件（Main.java）
接口如下：

1. package com.spring.test.service;
3. public interface UserService {
4. <?xml version="1.0" encoding="UTF-8"?>
5. <beans xmlns="http://www.springframework.org/schema/beans"
6.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
7.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
8.         <bean id="userService" />
9. </beans>public String getName();
10. }

复制代码

实现类

1. package com.spring.test.impl;
3. import com.spring.test.service.UserService;
5. public class UserServiceImpl implements UserService {
6. <?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>@Override
12. <?xml version="1.0" encoding="UTF-8"?>
13. <beans xmlns="http://www.springframework.org/schema/beans"
14.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
15.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
16.         <bean id="userService" />
17. </beans>public String getName() {
18. <?xml version="1.0" encoding="UTF-8"?>
19. <beans xmlns="http://www.springframework.org/schema/beans"
20.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
21.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
22.         <bean id="userService" />
23. </beans><?xml version="1.0" encoding="UTF-8"?>
24. <beans xmlns="http://www.springframework.org/schema/beans"
25.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
26.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
27.         <bean id="userService" />
28. </beans>return "Hello World";
29. <?xml version="1.0" encoding="UTF-8"?>
30. <beans xmlns="http://www.springframework.org/schema/beans"
31.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
32.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
33.         <bean id="userService" />
34. </beans>}
35. }

复制代码

Main代码如下

1. public class Test {
2. <?xml version="1.0" encoding="UTF-8"?>
3. <beans xmlns="http://www.springframework.org/schema/beans"
4.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
5.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
6.         <bean id="userService" />
7. </beans>public static void main(String[] args) {
8. <?xml version="1.0" encoding="UTF-8"?>
9. <beans xmlns="http://www.springframework.org/schema/beans"
10.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
11.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
12.         <bean id="userService" />
13. </beans><?xml version="1.0" encoding="UTF-8"?>
14. <beans xmlns="http://www.springframework.org/schema/beans"
15.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
16.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
17.         <bean id="userService" />
18. </beans>ApplicationContext context =
19. <?xml version="1.0" encoding="UTF-8"?>
20. <beans xmlns="http://www.springframework.org/schema/beans"
21.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
22.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
23.         <bean id="userService" />
24. </beans><?xml version="1.0" encoding="UTF-8"?>
25. <beans xmlns="http://www.springframework.org/schema/beans"
26.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
27.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
28.         <bean id="userService" />
29. </beans><?xml version="1.0" encoding="UTF-8"?>
30. <beans xmlns="http://www.springframework.org/schema/beans"
31.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
32.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
33.         <bean id="userService" />
34. </beans><?xml version="1.0" encoding="UTF-8"?>
35. <beans xmlns="http://www.springframework.org/schema/beans"
36.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
37.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
38.         <bean id="userService" />
39. </beans>new ClassPathXmlApplicationContext("classpath*:application.xml");
41. <?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>UserService userService = context.getBean(UserService.class);
52. <?xml version="1.0" encoding="UTF-8"?>
53. <beans xmlns="http://www.springframework.org/schema/beans"
54.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
55.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
56.         <bean id="userService" />
57. </beans><?xml version="1.0" encoding="UTF-8"?>
58. <beans xmlns="http://www.springframework.org/schema/beans"
59.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
60.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
61.         <bean id="userService" />
62. </beans>System.out.println(userService);
63. <?xml version="1.0" encoding="UTF-8"?>
64. <beans xmlns="http://www.springframework.org/schema/beans"
65.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
66.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
67.         <bean id="userService" />
68. </beans><?xml version="1.0" encoding="UTF-8"?>
69. <beans xmlns="http://www.springframework.org/schema/beans"
70.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
71.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
72.         <bean id="userService" />
73. </beans>// 这句将输出: hello world
74. <?xml version="1.0" encoding="UTF-8"?>
75. <beans xmlns="http://www.springframework.org/schema/beans"
76.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
77.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
78.         <bean id="userService" />
79. </beans><?xml version="1.0" encoding="UTF-8"?>
80. <beans xmlns="http://www.springframework.org/schema/beans"
81.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
82.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
83.         <bean id="userService" />
84. </beans>System.out.println(userService.getName());
86. <?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans>}
92. }

复制代码

配置文件 application.xml（在 resources 中）配置如下：

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>

复制代码

运行

1. 输出如下
2. com.spring.test.impl.UserServiceImpl@2aa5fe93
3. Hello World

复制代码

1.4 工厂的构建

1. 引言：
2. 接下来，我们就正式讲解Spring ioC容器的源码
3. 我们的目的：看一下ioC如何帮我们生成对象的

复制代码

生命周期

1）ApplicationContext入口

参考 IocTest.java
测试代码：spring支持多种bean定义方式，为方便大家理解结构，以xml为案例，后面的解析流程一致

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans><?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>ApplicationContext context = new ClassPathXmlApplicationContext("classpath*:${xmlName}.xml");<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>// （c）从容器中取出Bean的实例，call：AbstractApplicationContext.getBean(java.lang.Class)<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>//工厂模式(simple)<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans>UserService userService = (UserService) context.getBean("userServiceBeanId");<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>// 这句将输出: hello world<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans>System.out.println(userService.getName());

复制代码

进入到ClassPathXmlApplicationContext的有参构造器
org.springframework.context.support.ClassPathXmlApplicationContext#ClassPathXmlApplicationContext(java.lang.String[], boolean, org.springframework.context.ApplicationContext)

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public ClassPathXmlApplicationContext(<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>String[] configLocations, boolean refresh, @Nullable ApplicationContext parent)<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>throws BeansException {<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>//继承结构图<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>//1、返回一个classloader<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>//2、返回一个解析器<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>super(parent);<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans><?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>// 1、获取环境（系统环境、jvm环境）<?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans><?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans>// 2、设置Placeholder占位符解析器<?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans><?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans>// 2、将xml的路径解析完存储到数组<?xml version="1.0" encoding="UTF-8"?>
107. <beans xmlns="http://www.springframework.org/schema/beans"
108.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
109.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
110.         <bean id="userService" />
111. </beans><?xml version="1.0" encoding="UTF-8"?>
112. <beans xmlns="http://www.springframework.org/schema/beans"
113.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
114.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.         <bean id="userService" />
116. </beans>setConfigLocations(configLocations);<?xml version="1.0" encoding="UTF-8"?>
117. <beans xmlns="http://www.springframework.org/schema/beans"
118.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
119.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
120.         <bean id="userService" />
121. </beans><?xml version="1.0" encoding="UTF-8"?>
122. <beans xmlns="http://www.springframework.org/schema/beans"
123.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
124.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
125.         <bean id="userService" />
126. </beans>//默认为true<?xml version="1.0" encoding="UTF-8"?>
127. <beans xmlns="http://www.springframework.org/schema/beans"
128.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
129.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
130.         <bean id="userService" />
131. </beans><?xml version="1.0" encoding="UTF-8"?>
132. <beans xmlns="http://www.springframework.org/schema/beans"
133.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
134.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
135.         <bean id="userService" />
136. </beans>if (refresh) {<?xml version="1.0" encoding="UTF-8"?>
137. <beans xmlns="http://www.springframework.org/schema/beans"
138.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
139.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
140.         <bean id="userService" />
141. </beans><?xml version="1.0" encoding="UTF-8"?>
142. <beans xmlns="http://www.springframework.org/schema/beans"
143.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
144.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
145.         <bean id="userService" />
146. </beans><?xml version="1.0" encoding="UTF-8"?>
147. <beans xmlns="http://www.springframework.org/schema/beans"
148.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
149.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
150.         <bean id="userService" />
151. </beans>//核心方法（模板）<?xml version="1.0" encoding="UTF-8"?>
152. <beans xmlns="http://www.springframework.org/schema/beans"
153.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
154.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
155.         <bean id="userService" />
156. </beans><?xml version="1.0" encoding="UTF-8"?>
157. <beans xmlns="http://www.springframework.org/schema/beans"
158.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
159.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
160.         <bean id="userService" />
161. </beans><?xml version="1.0" encoding="UTF-8"?>
162. <beans xmlns="http://www.springframework.org/schema/beans"
163.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
164.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
165.         <bean id="userService" />
166. </beans>refresh();<?xml version="1.0" encoding="UTF-8"?>
167. <beans xmlns="http://www.springframework.org/schema/beans"
168.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
169.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
170.         <bean id="userService" />
171. </beans><?xml version="1.0" encoding="UTF-8"?>
172. <beans xmlns="http://www.springframework.org/schema/beans"
173.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
174.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
175.         <bean id="userService" />
176. </beans>}<?xml version="1.0" encoding="UTF-8"?>
177. <beans xmlns="http://www.springframework.org/schema/beans"
178.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
179.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
180.         <bean id="userService" />
181. </beans>}

复制代码

重点步骤解析（断点跟踪讲解）

1. super方法做了哪些事情
2. 1、super方法：通过点查看父容器与子容器概念
3. 2、super方法：调用到顶端，一共5层，每一层都要与讲义中的【ioC与Bean工厂类关系继承】进行对照
4. 3、super方法：在什么地方初始化的类加载器和解析器
5. setConfigLocations方法做了哪些事情：
6. 1、如何返回的系统环境和jvm环境
7. 2、路径的解析
8. 3、设置占位符解析器
10. 进入核心方法refresh

复制代码

2）预刷新

prepareRefresh()【准备刷新】

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans><?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>// synchronized块锁（monitorenter --monitorexit），不然 refresh() 还没结束，又来个启动或销毁容器的操作<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>synchronized (this.startupShutdownMonitor) {<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>//1、【准备刷新】【Did four things】<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>prepareRefresh();<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans><?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans><?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans><?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>......。略

复制代码

讲解重点（断点跟踪、类继承关系、架构图讲解）

1. prepareRefresh干了哪些事情<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>//1、记录启动时间/设置开始标志<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>//2、子类属性扩展（模板方法）<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>//3、校验xml配置文件<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>//4、初始化早期发布的应用程序事件对象（不重要，仅仅是创建setg对象）

复制代码

3）创建bean工厂【重点】

【获得新的bean工厂】obtainFreshBeanFactory()
最终目的就是解析xml，注册bean定义

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans><?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>关键步骤<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>//1、关闭旧的 BeanFactory<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>//2、创建新的 BeanFactory（DefaluListbaleBeanFactory）<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans>//3、解析xml/加载 Bean 定义、注册 Bean定义到beanFactory(未初始化)<?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans><?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>//4、返回全新的工厂<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans><?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans><?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans>ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

复制代码

4）bean工厂前置操作

【准备bean工厂】prepareBeanFactory(beanFactory);

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>//1、设置 BeanFactory 的类加载器<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>//2、设置 BeanFactory 的表达式解析器<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>//3、设置 BeanFactory 的属性编辑器<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>//4、智能注册

复制代码

tips
当前代码逻辑简单、且非核心

5）bean工厂后置操作

【后置处理器Bean工厂】postProcessBeanFactory(beanFactory)    空方法

tips：子类实现
空方法，跳过

6）工厂后置处理器【重点】

【调用bean工厂后置处理器】invokeBeanFactoryPostProcessors(beanFactory);

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>//调用顺序一：bean定义注册后置处理器<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>//调用顺序二：bean工厂后置处理器<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>PostProcessorRegistrationDelegate 类里有详细注解

复制代码

tips
invoke方法近200行
关注两类后置处理器的方法执行步骤和顺序

7）bean后置处理器

【注册bean后置处理器】registerBeanPostProcessors(beanFactory)

1. //6、【注册bean后置处理器】只是注册，但是不会反射调用
2. //功能：找出所有实现BeanPostProcessor接口的类,分类、排序、注册
3. registerBeanPostProcessors(beanFactory);

复制代码

1. //<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>核心：查看重要的3步；最终目的都是实现bean后置处理器的注册// 第一步： implement PriorityOrdered// 第二步： implement Ordered.// 第三步： Register all internal BeanPostProcessors.

复制代码

8）国际化

【初始化消息源】国际化问题i18n   initMessageSource();

tips：
就加了个bean进去，非核心步骤，跳过

9）初始化事件广播器

【初始化应用程序事件多路广播】initApplicationEventMulticaster();

tips：
需要讲解观察者设计模式
重点：就放了个bean进去， 到下面的 listener再联调。

10）刷新

【刷新】 onRefresh();
空的，交给子类实现：默认情况下不执行任何操作

1. // 具体的子类可以在这里初始化一些特殊的 Bean（在初始化 singleton beans 之前）
2. onRefresh();
4. 不重要，跳过

复制代码

11）注册监听器【重点】

【注册所有监听器】registerListeners();
测试代码参考：MulticastTest

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>//获取所有实现了ApplicationListener，然后进行注册<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>//1、集合applicationListeners查找<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>//2、bean工厂找到实现ApplicationListener接口的bean<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>//3、this.earlyApplicationEvents；

复制代码

tips：
需要讲解观察者设计模式
重点：演示多播和容器发布

12）完成bean工厂【重点】

【完成bean工厂初始化操作】finishBeanFactoryInitialization(beanFactory);

1. //【完成bean工厂初始化操作】负责初始化所有的 singleton beans
2. //此处开始调用Bean的前置处理器和后置处理器
3. finishBeanFactoryInitialization(beanFactory);

复制代码

讲解重点（断点跟踪、类继承关系、架构图讲解）

1.   //1、设置辅助器：例如：解析器、转换器、类装载器<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>//2、实例化<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>//3、填充<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>//4、调用前置、后置处理器

复制代码

1. //核心代码在  getBean() , 下面单独讲解

复制代码

13）完成刷新

【完成刷新】

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>protected void finishRefresh() {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>// 1、清除上下文级资源缓存<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>clearResourceCaches();<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>// 2、LifecycleProcessor接口初始化<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>// ps：当ApplicationContext启动或停止时，它会通过LifecycleProcessor来与所有声明的bean的周期做状态更新<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>// 而在LifecycleProcessor的使用前首先需要初始化<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>initLifecycleProcessor();<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>// 3、启动所有实现了LifecycleProcessor接口的bean<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans><?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>//DefaultLifecycleProcessor,默认实现<?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans><?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans>getLifecycleProcessor().onRefresh();<?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans><?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans>// 4、发布上下文刷新完毕事件到相应的监听器<?xml version="1.0" encoding="UTF-8"?>
107. <beans xmlns="http://www.springframework.org/schema/beans"
108.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
109.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
110.         <bean id="userService" />
111. </beans><?xml version="1.0" encoding="UTF-8"?>
112. <beans xmlns="http://www.springframework.org/schema/beans"
113.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
114.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.         <bean id="userService" />
116. </beans>//ps：当完成容器初始化的时候，<?xml version="1.0" encoding="UTF-8"?>
117. <beans xmlns="http://www.springframework.org/schema/beans"
118.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
119.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
120.         <bean id="userService" />
121. </beans><?xml version="1.0" encoding="UTF-8"?>
122. <beans xmlns="http://www.springframework.org/schema/beans"
123.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
124.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
125.         <bean id="userService" />
126. </beans>// 要通过Spring中的事件发布机制来发出ContextRefreshedEvent事件，以保证对应的监听器可以做进一步的逻辑处理<?xml version="1.0" encoding="UTF-8"?>
127. <beans xmlns="http://www.springframework.org/schema/beans"
128.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
129.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
130.         <bean id="userService" />
131. </beans><?xml version="1.0" encoding="UTF-8"?>
132. <beans xmlns="http://www.springframework.org/schema/beans"
133.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
134.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
135.         <bean id="userService" />
136. </beans>publishEvent(new ContextRefreshedEvent(this));<?xml version="1.0" encoding="UTF-8"?>
137. <beans xmlns="http://www.springframework.org/schema/beans"
138.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
139.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
140.         <bean id="userService" />
141. </beans><?xml version="1.0" encoding="UTF-8"?>
142. <beans xmlns="http://www.springframework.org/schema/beans"
143.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
144.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
145.         <bean id="userService" />
146. </beans>// 5、把当前容器注册到到MBeanServer，用于jmx使用<?xml version="1.0" encoding="UTF-8"?>
147. <beans xmlns="http://www.springframework.org/schema/beans"
148.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
149.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
150.         <bean id="userService" />
151. </beans><?xml version="1.0" encoding="UTF-8"?>
152. <beans xmlns="http://www.springframework.org/schema/beans"
153.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
154.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
155.         <bean id="userService" />
156. </beans>LiveBeansView.registerApplicationContext(this);<?xml version="1.0" encoding="UTF-8"?>
157. <beans xmlns="http://www.springframework.org/schema/beans"
158.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
159.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
160.         <bean id="userService" />
161. </beans>}

复制代码

tips:
非核心步骤

2 singleton bean 创建【重点】

下面拎出来，重点讲 getBean方法。
参考代码：
先看没有循环依赖的情况，普通单例bean的初始化   SinigleTest.java
后面再讲循环依赖
1）调用入口

大家都知道是getBean()方法，但是这个方法要注意，有很多调用时机
如果你把断点打在了这里，再点进去getBean，你将会直接从singleton集合中拿到一个实例化好的bean
无法看到它的实例化过程。
可以debug试一下。会发现直接从getSingleTon返回了bean，这不是我们想要的模样……

思考一下，为什么呢？
回顾 1.4中的第 12 小节，在bean工厂完成后，会对singleton的bean完成初始化，那么真正的初始化应该发生在那里！
那就需要找到：DefaultListableBeanFactory的第 809 行，那里的getBean
也可以从 1.4的第12小节的入口跟进去。断点打在这里试试：

这也是我们在上面留下的尾巴。
本小节我们从这里继续……
2）主流程

小tip：先搞清除3级缓存的事
关于bean的三级缓存：DefaultSingletonBeanRegistry代码

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>/**<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans> * 一级缓存：单例（对象）池，这里面的对象都是确保初始化完成，可以被正常使用的<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans> * 它可能来自3级，或者2级<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans> */<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>private final Map singletonObjects = new ConcurrentHashMap(256);<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>/**<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans> * 三级缓存：单例工厂池，这里面不是bean本身，是它的一个工厂，未来调getObject来获取真正的bean<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans> * 一旦获取，就从这里删掉，进入2级（发生闭环的话）或1级（没有闭环）<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans> */<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>private final Map></p></blockquote>[b]变化过程3-3:如下图：[/b]
52. [img]https://img2022.cnblogs.com/other/2893049/202210/2893049-20221026150702299-1554045943.png[/img]
53. [indent]步骤：
54. 此时, BeanB里面已经注入了BeanA，它自己完成并进入了一级缓存
55. 要注意，它的完成是被动的结果，也就是A需要它，临时先腾出时间创建了它
56. 接下来，BeanA 还要继续自己的流程，然后populateBean方法将BeanB注入到自己里
57. 最后，BeanA 进一级缓存，删除之前的二级
58. 整个流程完成！
59. [/indent][b]大功告成：双方相互持有对方效果如下：[/b]
60. [img]https://img2022.cnblogs.com/other/2893049/202210/2893049-20221026150703512-1723493531.png[/img]
61. [size=3]2）三级缓存解决方案总结[/size]
63. 简化版
64. [img]https://img2022.cnblogs.com/other/2893049/202210/2893049-20221026150703903-145488494.png[/img]
65. 序列图
66. [img]https://img2022.cnblogs.com/other/2893049/202210/2893049-20221026150704317-2067633481.png[/img]
67. [b]三级缓存解决循环依赖过程（回顾）[/b]
68. 1、BeanA经过gdcd方法、放入到3级缓存、如果有循环依赖BeanB，重复执行gdcd方法
69. 2、直到发现了它也需要A，而A前面经历了一次get操作，将3级缓存的BeanA放到2级缓存
70. 3、然后2级缓存的A注入进BeanB,  BeanB完事进一级缓存，此时BeanB持有BeanA
71. 3、接下来，继续完成BeanA剩下的操作，取BeanB填充进BeanA，将BeanA放到一级缓存，完成！
72. [b]伪代码，循环依赖流程一览，都是关键步骤，不能再简化了[/b]
73. 建议粘贴到vscode等编辑器里查看，因为……它层级太tmd深了！
74. [code]getBean("A"){<?xml version="1.0" encoding="UTF-8"?>
75. <beans xmlns="http://www.springframework.org/schema/beans"
76.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
77.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
78.         <bean id="userService" />
79. </beans>doGetBean("A"){    a = getSingleton("A"){      a = singletonObjects(); //查1级缓存，null      if("创建过3级缓存"){  //不成立        //忽略      }      return a;    }; // A第一次，null        if(a == null){      a = getSingleton("A" , ObjectFactory of){                        a = of.getObject() -> { //lambda表达式          createBean("A"){            doCreateBean("A"){              createBeanInstance("A"); // A 实例化              addSingletonFactory("A"); // A 放入3级缓存              populateBean("A"){                //A 需要B，进入B的getBean                b = getBean("B"){                  doGetBean("B"){                    b = getSingleton("B"); // B第一次，null                    if(b == null){                      b = getSingleton("B", ObjectFactory of){                        b = of.getObject() -> {                          createBean("B"){                            doCreateBean("B"){                              createBeanInstance("B"); // B 实例化                              addSingletonFactory("B"); // B 放入3级缓存                              populateBean("B"){                                //B 需要A，2次进入A的getBean                                a = getBean("A"){                                  doGetBean("A"){                                    a = getSingleton("A"){                                      a = singletonObjects(); //查1级缓存，null                                      if("创建过3级缓存"){  //成立！                                        a = singletonFactory.getObject("A"); //取3级缓存，生成a                                        earlySingletonObjects.put("A", a); //放入2级缓存                                        singletonFactories.remove("A"); //移除3级缓存                                        return a;                                      }                                    }; // A第二次，不是null，但是半成品，还待在2级缓存里                                  } // end doGetBean("A")                                } // end getBean("A")                              }  // end populate B                              initializeBean("B",b); // B后置处理器                            } // end doCreateBean B                          } // end createBean B                        } // end lambda B                        // B 创建完成，并且是完整的，虽然它里面的A还是半成品，但不影响它进入1级                                       addSingleton("B",b) ; // 清除3级缓存，进入1级                      ); // end getSingleton("B",factory)                                     } // end if(b==null);                    return b;                  } // end doGetBean("B")                } // end getBean("B")              } // end populateBean("A")              initializeBean("A"); // A 后置处理器            } //end doCreateBean("A")          } //end crateBean("A")      <?xml version="1.0" encoding="UTF-8"?>
80. <beans xmlns="http://www.springframework.org/schema/beans"
81.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
82.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
83.         <bean id="userService" />
84. </beans>} // end lambda A                addSingleton("A" , a) // 清除2、3级，放入1级      } // end getSingleton("A",factory)      } // end if(a == null)        return a;        } //end doGetBean("A")}//end getBean("A")

复制代码

总结
可以发现，通过spring的三级缓存完美解决了循环依赖
Spring处理机制很聪明；它先扫描一遍Bean，先放到一个容器（3级缓存待命）
此时也不知道是否存在循环依赖，先放到三级缓存再说
等到设置属性的时候，取对应的属性bean去（此时才发现有了循环依赖） ，在放到第二个容器（2级缓存，半成品）
继续，然后从二级缓存拿出进行填充（注入）
填充完毕，将自己放到一级缓存（这个bean是被动创建出来的，因为别人需要它，结果它先完成了）
然后不断循环外层，处理最原始要创建的那个bean
为什么设计三级？二级缓存能否解决循环依赖？
可以解决。别说2级，1级都行
虽然二级缓存能解决循环依赖，但是aop时会可能会引发问题，三级是一个factory，在里面配备了对应的后置处理器，其中就有我们的aop （后面会讲到），如果有人要用它，会在调用factory的getObject时生效，生成代理bean而不是原始bean。
如果不这么做，直接创建原始对象注入，可能引发aop失效。
所以spring的3级各有意义：
1级：最终成品
2级：半成品
3级：工厂，备用
在上面的方法getEarlyBeanReference（提前暴露的引用）
回顾下
AbstractAutowireCapableBeanFactory.getEarlyBeanReference

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans><?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>//循环所有Bean后置处理器<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans>for (BeanPostProcessor bp : getBeanPostProcessors()) {<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans>if (bp instanceof SmartInstantiationAwareBeanPostProcessor) {<?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans><?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans><?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans><?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>SmartInstantiationAwareBeanPostProcessor ibp = (SmartInstantiationAwareBeanPostProcessor) bp;<?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans><?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans><?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans><?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans>  //重点：开始创建AOP代理<?xml version="1.0" encoding="UTF-8"?>
107. <beans xmlns="http://www.springframework.org/schema/beans"
108.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
109.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
110.         <bean id="userService" />
111. </beans><?xml version="1.0" encoding="UTF-8"?>
112. <beans xmlns="http://www.springframework.org/schema/beans"
113.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
114.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.         <bean id="userService" />
116. </beans><?xml version="1.0" encoding="UTF-8"?>
117. <beans xmlns="http://www.springframework.org/schema/beans"
118.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
119.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
120.         <bean id="userService" />
121. </beans><?xml version="1.0" encoding="UTF-8"?>
122. <beans xmlns="http://www.springframework.org/schema/beans"
123.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
124.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
125.         <bean id="userService" />
126. </beans><?xml version="1.0" encoding="UTF-8"?>
127. <beans xmlns="http://www.springframework.org/schema/beans"
128.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
129.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
130.         <bean id="userService" />
131. </beans>exposedObject = ibp.getEarlyBeanReference(exposedObject, beanName);<?xml version="1.0" encoding="UTF-8"?>
132. <beans xmlns="http://www.springframework.org/schema/beans"
133.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
134.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
135.         <bean id="userService" />
136. </beans><?xml version="1.0" encoding="UTF-8"?>
137. <beans xmlns="http://www.springframework.org/schema/beans"
138.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
139.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
140.         <bean id="userService" />
141. </beans><?xml version="1.0" encoding="UTF-8"?>
142. <beans xmlns="http://www.springframework.org/schema/beans"
143.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
144.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
145.         <bean id="userService" />
146. </beans><?xml version="1.0" encoding="UTF-8"?>
147. <beans xmlns="http://www.springframework.org/schema/beans"
148.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
149.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
150.         <bean id="userService" />
151. </beans>}<?xml version="1.0" encoding="UTF-8"?>
152. <beans xmlns="http://www.springframework.org/schema/beans"
153.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
154.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
155.         <bean id="userService" />
156. </beans><?xml version="1.0" encoding="UTF-8"?>
157. <beans xmlns="http://www.springframework.org/schema/beans"
158.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
159.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
160.         <bean id="userService" />
161. </beans><?xml version="1.0" encoding="UTF-8"?>
162. <beans xmlns="http://www.springframework.org/schema/beans"
163.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
164.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
165.         <bean id="userService" />
166. </beans>}<?xml version="1.0" encoding="UTF-8"?>
167. <beans xmlns="http://www.springframework.org/schema/beans"
168.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
169.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
170.         <bean id="userService" />
171. </beans><?xml version="1.0" encoding="UTF-8"?>
172. <beans xmlns="http://www.springframework.org/schema/beans"
173.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
174.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
175.         <bean id="userService" />
176. </beans>}

复制代码

总结下：
1、如果不调用后置处理器，返回的Bean和三级缓存一样,都是实例化、普通的Bean
2、如果调用后置，返回的就是代理对象，不是普通的Bean了
其实；这就是三级缓存设计的巧妙之处
那为什么要2级呢？ 不能直接放入1级吗？
不能！
A-B-A中，第二次A的时候，A还是个半成品，不能放入1级
以上面为例，A在进入2级缓存的时候，它里面的B还是个null ！
如果放入1级，被其他使用的地方取走，会引发问题，比如空指针
4 IoC用到的那些设计模式

1. //啥也没干，调下面传了个true
2. public Object getSingleton(String beanName)
3.   
4. //从1级缓存拿，1级没有再看情况
5. //后面的参数如果true，就使用3级升2级返回，否则直接返回null
6. protected Object getSingleton(String beanName, boolean allowEarlyReference)
8. //1级没有，通过给的factory创建并放入1级里，清除2、3
9. public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory)

复制代码

4.1 工厂

工厂模式（Factory Pattern）提供了一种创建对象的最佳方式。
工厂模式（Factory Pattern）分为三种
1、简单工厂
2、工厂方法
3、抽象工厂
1. 简单工厂模式

1. ApplicationContext context =<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>new ClassPathXmlApplicationContext("classpath*:application.xml");\UserService userService = context.getBean(UserService.class);

复制代码

简单工厂模式对对象创建管理方式最为简单，因为其仅仅简单的对不同类对象的创建进行了一层简单的封装
定义接口IPhone

1. public interface Phone {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>void make();}

复制代码

实现类

1. public class IPhone implements Phone {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public IPhone() {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>this.make();<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>}<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>public void make() {<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans>// TODO Auto-generated method stub<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>System.out.println("生产苹果手机!");<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>}}

复制代码

实现类

1. public class MiPhone implements Phone {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public MiPhone() {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>this.make();<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>}<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>public void make() {<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans>// TODO Auto-generated method stub<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>System.out.println("生产小米手机!");<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>}}

复制代码

定义工厂类并且测试

1. public class PhoneFactory {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public Phone makePhone(String phoneType) {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>if (phoneType.equalsIgnoreCase("MiPhone")) {<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>return new MiPhone();<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans><?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans>} else if (phoneType.equalsIgnoreCase("iPhone")) {<?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>return new IPhone();<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>}<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>return null;<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>}<?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>//测试简单工厂<?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans>public static void main(String[] arg) {<?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans><?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans>PhoneFactory factory = new PhoneFactory();<?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans><?xml version="1.0" encoding="UTF-8"?>
107. <beans xmlns="http://www.springframework.org/schema/beans"
108.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
109.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
110.         <bean id="userService" />
111. </beans>Phone miPhone = factory.makePhone("MiPhone");             <?xml version="1.0" encoding="UTF-8"?>
112. <beans xmlns="http://www.springframework.org/schema/beans"
113.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
114.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.         <bean id="userService" />
116. </beans><?xml version="1.0" encoding="UTF-8"?>
117. <beans xmlns="http://www.springframework.org/schema/beans"
118.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
119.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
120.         <bean id="userService" />
121. </beans>IPhone iPhone = (IPhone) factory.makePhone("iPhone");     <?xml version="1.0" encoding="UTF-8"?>
122. <beans xmlns="http://www.springframework.org/schema/beans"
123.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
124.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
125.         <bean id="userService" />
126. </beans>}}

复制代码

4.2  模板

模板模式(Template Pattern):基于抽象类的，核心是封装算法

1. 引言
2. 在上面，我们剖析了bean实例化的整个过程
3. 也就是我们的Bean他是单独存在的，和其他Bean没有交集和引用
4. 而我们在业务开发中，肯定会有多个Bean相互引用的情况
5. 也就是所谓的循环依赖

复制代码

模板设计模式—
模板方法定义了一个算法的步骤，并允许子类为一个或多个步骤提供具体实现

1. //模板模式public abstract class TemplatePattern {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>protected abstract void step1();<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>protected abstract void step2();<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>protected abstract void step3();<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>protected abstract void step4();<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>//模板方法<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>public final void refresh() {<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>//此处也可加入当前类的一个方法实现，例如init()<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>step1();<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>step2();<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>step3();<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>step4();<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>}}

复制代码

定义子类

1. //模板模式public class SubTemplatePattern extends TemplatePattern {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>public void step1() {<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>System.out.println(">>>>>>>>>>>>>>1");<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>}<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>public void step2() {<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>System.out.println(">>>>>>>>>>>>>>2");<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>}<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans>public void step3() {<?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans><?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans>System.out.println(">>>>>>>>>>>>>>3");<?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>}<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans>public void step4() {<?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans><?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans>System.out.println(">>>>>>>>>>>>>>4");<?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans>}        //测试<?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans>public static void main(String[] args) {<?xml version="1.0" encoding="UTF-8"?>
107. <beans xmlns="http://www.springframework.org/schema/beans"
108.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
109.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
110.         <bean id="userService" />
111. </beans><?xml version="1.0" encoding="UTF-8"?>
112. <beans xmlns="http://www.springframework.org/schema/beans"
113.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
114.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.         <bean id="userService" />
116. </beans>TemplatePattern tp = new SubTemplatePattern();<?xml version="1.0" encoding="UTF-8"?>
117. <beans xmlns="http://www.springframework.org/schema/beans"
118.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
119.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
120.         <bean id="userService" />
121. </beans><?xml version="1.0" encoding="UTF-8"?>
122. <beans xmlns="http://www.springframework.org/schema/beans"
123.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
124.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
125.         <bean id="userService" />
126. </beans>tp.refresh();<?xml version="1.0" encoding="UTF-8"?>
127. <beans xmlns="http://www.springframework.org/schema/beans"
128.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
129.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
130.         <bean id="userService" />
131. </beans>}}

复制代码

输出

4.3 观察者

什么是观察者模式
观察者模式(Observer Pattern)：当对象间存在一对多关系时，则使用观察者模式（Observer Pattern）。比如，当一个对象被修改时，则会自动通知依赖它的对象。
Spring 的事件机制就是具体的观察者模式的实现

1. //实现类
2. public class UserServiceImplB implements UserService {
3.         private UserServiceImplA userServiceImplA;
5.         public void setUserServiceImplA(UserServiceImplA userServiceImplA) {
6.                 this.userServiceImplA = userServiceImplA;
7.         }
9.         @Override
10.         public String getName() {
12.                 return "在UserServiceImplB的Bean中" +
13.                                 "userServiceImplA注入成功>>>>>>>>>"+userServiceImplA;
15.         }

复制代码

观察者模式有哪些角色？
事件 ApplicationEvent 是所有事件对象的父类，继承JDK的EventObject
事件监听 ApplicationListener，也就是观察者对象，继承自 JDK 的 EventListener,可以监听到事件；该类中只有一个方法 onApplicationEvent。当监听的事件发生后该方法会被执行。
事件发布ApplicationContext， 实现事件的发布。
（发布事件）
or=========
Spring中的多播
事件发布 ApplicationEventMulticaster，用于事件监听器的注册和事件的广播。

自定义一个事件MessageSourceEvent并且实现ApplicationEvent接口

1. //在Spring 中使用事件监听机制(事件、监听、发布)//定义事件//执行顺序//1、进入到事件源的有参数构造器//2、发布事件//3、进入到监听器类---one//4、进入到事件源的方法//5、进入到监听器类---two//6、进入到事件源的方法public class MessageSourceEvent extends ApplicationEvent {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public MessageSourceEvent(Object source) {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>super(source);<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>System.out.println("进入到事件源的有参数构造器");<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>}<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>public void print() {<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>System.out.println("进入到事件源的方法");<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>}}

复制代码

有了事件之后还需要自定义一个监听用来接收监听到事件，自定义ApplicationContextListener监听 需要交给Spring容器管理， 实现ApplicationListener接口并且重写onApplicationEvent方法，
监听一

1. //在Spring 中使用事件监听机制(事件、监听、发布)//监听类，在spring配置文件中,注册事件类和监听类public class ApplicationContextListener implements ApplicationListener {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>public void onApplicationEvent(ApplicationEvent event) {<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>if (event instanceof MessageSourceEvent) {<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>System.out.println("进入到监听器类---one");<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>MessageSourceEvent myEvent = (MessageSourceEvent) event;<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>myEvent.print();<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>}<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>}}

复制代码

监听二

1. //在Spring 中使用事件监听机制(事件、监听、发布)//监听类，在spring配置文件中,注册事件类和监听类public class ApplicationContextListenerTwo implements ApplicationListener  {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>public void onApplicationEvent(ApplicationEvent event) {<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans>if(event instanceof MessageSourceEvent){<?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>System.out.println("进入到监听器类---two");<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans><?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans>MessageSourceEvent myEvent=(MessageSourceEvent)event;<?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans><?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>myEvent.print();<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>}<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>}}

复制代码

发布事件

1. //在Spring 中使用事件监听机制(事件、监听、发布)//该类实现ApplicationContextAware接口,得到ApplicationContext对象// 使用该对象的publishEvent方法发布事件public class ApplicationContextListenerPubisher implements ApplicationContextAware {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>private ApplicationContext applicationContext;<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans>@Override<?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans>this.applicationContext = applicationContext;<?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>}<?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>public void publishEvent(ApplicationEvent event) {<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>System.out.println("发布事件");<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>applicationContext.publishEvent(event);<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans>}}

复制代码

配置文件

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans><?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans><?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans>

复制代码

测试

1. //总结 ：使用bean工厂发布和使用多播器效果是一样的public class Test {<?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
5.         <bean id="userService" />
6. </beans>public static void main(String[] args) {<?xml version="1.0" encoding="UTF-8"?>
7. <beans xmlns="http://www.springframework.org/schema/beans"
8.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
9.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
10.         <bean id="userService" />
11. </beans><?xml version="1.0" encoding="UTF-8"?>
12. <beans xmlns="http://www.springframework.org/schema/beans"
13.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
14.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.         <bean id="userService" />
16. </beans>ApplicationContext context =<?xml version="1.0" encoding="UTF-8"?>
17. <beans xmlns="http://www.springframework.org/schema/beans"
18.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
19.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
20.         <bean id="userService" />
21. </beans><?xml version="1.0" encoding="UTF-8"?>
22. <beans xmlns="http://www.springframework.org/schema/beans"
23.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
24.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
25.         <bean id="userService" />
26. </beans><?xml version="1.0" encoding="UTF-8"?>
27. <beans xmlns="http://www.springframework.org/schema/beans"
28.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
29.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.         <bean id="userService" />
31. </beans><?xml version="1.0" encoding="UTF-8"?>
32. <beans xmlns="http://www.springframework.org/schema/beans"
33.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
34.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
35.         <bean id="userService" />
36. </beans>new ClassPathXmlApplicationContext("classpath*:application.xml");<?xml version="1.0" encoding="UTF-8"?>
37. <beans xmlns="http://www.springframework.org/schema/beans"
38.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
39.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
40.         <bean id="userService" />
41. </beans><?xml version="1.0" encoding="UTF-8"?>
42. <beans xmlns="http://www.springframework.org/schema/beans"
43.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
44.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
45.         <bean id="userService" />
46. </beans>//***************使用spring的多播器发布**********************<?xml version="1.0" encoding="UTF-8"?>
47. <beans xmlns="http://www.springframework.org/schema/beans"
48.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
49.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
50.         <bean id="userService" />
51. </beans><?xml version="1.0" encoding="UTF-8"?>
52. <beans xmlns="http://www.springframework.org/schema/beans"
53.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
54.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
55.         <bean id="userService" />
56. </beans>ApplicationEventMulticaster applicationEventMulticaster = (ApplicationEventMulticaster) context.getBean("applicationEventMulticaster");<?xml version="1.0" encoding="UTF-8"?>
57. <beans xmlns="http://www.springframework.org/schema/beans"
58.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
59.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
60.         <bean id="userService" />
61. </beans><?xml version="1.0" encoding="UTF-8"?>
62. <beans xmlns="http://www.springframework.org/schema/beans"
63.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
64.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
65.         <bean id="userService" />
66. </beans>applicationEventMulticaster.multicastEvent(new MessageSourceEvent("测试..."));//***************使用BeanFactory的publishEvent发布*********************<?xml version="1.0" encoding="UTF-8"?>
67. <beans xmlns="http://www.springframework.org/schema/beans"
68.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
69.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.         <bean id="userService" />
71. </beans><?xml version="1.0" encoding="UTF-8"?>
72. <beans xmlns="http://www.springframework.org/schema/beans"
73.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
74.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
75.         <bean id="userService" />
76. </beans>//<?xml version="1.0" encoding="UTF-8"?>
77. <beans xmlns="http://www.springframework.org/schema/beans"
78.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
79.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
80.         <bean id="userService" />
81. </beans>ApplicationContextListenerPubisher myPubisher = (ApplicationContextListenerPubisher)<?xml version="1.0" encoding="UTF-8"?>
82. <beans xmlns="http://www.springframework.org/schema/beans"
83.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
84.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
85.         <bean id="userService" />
86. </beans><?xml version="1.0" encoding="UTF-8"?>
87. <beans xmlns="http://www.springframework.org/schema/beans"
88.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
89.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
90.         <bean id="userService" />
91. </beans>//context.getBean("applicationContextListenerPubisher");<?xml version="1.0" encoding="UTF-8"?>
92. <beans xmlns="http://www.springframework.org/schema/beans"
93.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
94.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
95.         <bean id="userService" />
96. </beans><?xml version="1.0" encoding="UTF-8"?>
97. <beans xmlns="http://www.springframework.org/schema/beans"
98.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
99.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
100.         <bean id="userService" />
101. </beans>//myPubisher.publishEvent(new MessageSourceEvent("测试..."));<?xml version="1.0" encoding="UTF-8"?>
102. <beans xmlns="http://www.springframework.org/schema/beans"
103.            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
104.            xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
105.         <bean id="userService" />
106. </beans>}}

复制代码

多播发布

工厂发布

总结：
​       1、spring的事件驱动模型使用的是 观察者模式
　　2、通过ApplicationEvent抽象类和ApplicationListener接口,可以实现事件处理
　　3、ApplicationEventMulticaster事件广播器实现了监听器的注册,一般不需要我们实现,只需要显示的调用    applicationcontext.publisherEvent方法即可
​        4、使用bean工厂发布和使用多播器效果是一样的

本文由传智教育博学谷教研团队发布。
如果本文对您有帮助，欢迎关注和点赞；如果您有任何建议也可留言评论或私信，您的支持是我坚持创作的动力。
转载请注明出处！

免责声明：如果侵犯了您的权益，请联系站长，我们会及时删除侵权内容，谢谢合作！