3、Spring之入门案例

3.1、创建module

3.1.1、右击project，创建新module


3.1.2、选择maven


3.1.3、设置module名称和路径



3.1.4、module初始状态


3.1.5、配置打包方式和依赖

1. <?xml version="1.0" encoding="UTF-8"?>
2. <project xmlns="http://maven.apache.org/POM/4.0.0"
3. <?xml version="1.0" encoding="UTF-8"?>
4. <beans xmlns="http://www.springframework.org/schema/beans"
5.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
6.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
8.    
9.     <bean id="helloWord" ></bean>
11. </beans> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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">
17.    
18.     <bean id="helloWord" ></bean>
20. </beans> xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
21.     <modelVersion>4.0.0</modelVersion>
23.     <groupId>org.rain</groupId>
24.     <artifactId>spring_helloword</artifactId>
25.     <version>1.0-SNAPSHOT</version>
26.     <packaging>jar</packaging>
28.     <dependencies>
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">
34.    
35.     <bean id="helloWord" ></bean>
37. </beans>
38. <?xml version="1.0" encoding="UTF-8"?>
39. <beans xmlns="http://www.springframework.org/schema/beans"
40.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
41.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
43.    
44.     <bean id="helloWord" ></bean>
46. </beans><dependency>
47. <?xml version="1.0" encoding="UTF-8"?>
48. <beans xmlns="http://www.springframework.org/schema/beans"
49.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
50.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
52.    
53.     <bean id="helloWord" ></bean>
55. </beans>    <groupId>org.springframework</groupId>
56. <?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">
61.    
62.     <bean id="helloWord" ></bean>
64. </beans>    <artifactId>spring-context</artifactId>
65. <?xml version="1.0" encoding="UTF-8"?>
66. <beans xmlns="http://www.springframework.org/schema/beans"
67.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
68.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
70.    
71.     <bean id="helloWord" ></bean>
73. </beans>    <version>5.3.1</version>
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">
79.    
80.     <bean id="helloWord" ></bean>
82. </beans></dependency>
83. <?xml version="1.0" encoding="UTF-8"?>
84. <beans xmlns="http://www.springframework.org/schema/beans"
85.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
86.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
88.    
89.     <bean id="helloWord" ></bean>
91. </beans>
92. <?xml version="1.0" encoding="UTF-8"?>
93. <beans xmlns="http://www.springframework.org/schema/beans"
94.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
95.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
97.    
98.     <bean id="helloWord" ></bean>
100. </beans><dependency>
101. <?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">
106.    
107.     <bean id="helloWord" ></bean>
109. </beans>    <groupId>junit</groupId>
110. <?xml version="1.0" encoding="UTF-8"?>
111. <beans xmlns="http://www.springframework.org/schema/beans"
112.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
113.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
115.    
116.     <bean id="helloWord" ></bean>
118. </beans>    <artifactId>junit</artifactId>
119. <?xml version="1.0" encoding="UTF-8"?>
120. <beans xmlns="http://www.springframework.org/schema/beans"
121.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
122.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
124.    
125.     <bean id="helloWord" ></bean>
127. </beans>    <version>4.12</version>
128. <?xml version="1.0" encoding="UTF-8"?>
129. <beans xmlns="http://www.springframework.org/schema/beans"
130.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
131.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
133.    
134.     <bean id="helloWord" ></bean>
136. </beans>    <scope>test</scope>
137. <?xml version="1.0" encoding="UTF-8"?>
138. <beans xmlns="http://www.springframework.org/schema/beans"
139.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
140.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
142.    
143.     <bean id="helloWord" ></bean>
145. </beans></dependency>
146.     </dependencies>
147. </project>

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3.2、示例

3.2.1、创建组件类

1. package org.rain.spring.component;
3. /**
4. * @author liaojy
5. * @date 2023/7/25 - 19:17
6. */
7. public class HelloWord {
9.     public void sayHello(){
10. <?xml version="1.0" encoding="UTF-8"?>
11. <beans xmlns="http://www.springframework.org/schema/beans"
12.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
13.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
15.    
16.     <bean id="helloWord" ></bean>
18. </beans>System.out.println("Hello,Spring!");
19.     }
20. }

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3.2.2、创建Sprig配置文件


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注意：因为会通过自定义代码指定Spring配置文件，所以Spring配置文件名可以是任意的；
但当整合ssm后，就不能通过通过自定义代码指定Spring配置文件，因此文件名有硬性要求。

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">
6.    
7.     <bean id="helloWord" ></bean>
9. </beans>

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3.2.3、创建测试类

如图所示，获取到了IOC容器和容器中对应的bean组件，并成功调用了该bean组件的方法

1. package org.rain.spring.test;import org.junit.Test;import org.rain.spring.component.HelloWord;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;/** * @author liaojy * @date 2023/7/25 - 19:39 */public class HelloWordTest {    @Test    public void testHelloWord(){<?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">
6.    
7.     <bean id="helloWord" ></bean>
9. </beans>//获取IOC容器<?xml version="1.0" encoding="UTF-8"?>
10. <beans xmlns="http://www.springframework.org/schema/beans"
11.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
12.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
14.    
15.     <bean id="helloWord" ></bean>
17. </beans>ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");<?xml version="1.0" encoding="UTF-8"?>
18. <beans xmlns="http://www.springframework.org/schema/beans"
19.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
20.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
22.    
23.     <bean id="helloWord" ></bean>
25. </beans>//获取IOC容器中的bean<?xml version="1.0" encoding="UTF-8"?>
26. <beans xmlns="http://www.springframework.org/schema/beans"
27.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
28.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.    
31.     <bean id="helloWord" ></bean>
33. </beans>HelloWord helloWord = (HelloWord)applicationContext.getBean("helloWord");<?xml version="1.0" encoding="UTF-8"?>
34. <beans xmlns="http://www.springframework.org/schema/beans"
35.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
36.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
38.    
39.     <bean id="helloWord" ></bean>
41. </beans>helloWord.sayHello();    }}

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3.3、获取bean的三种方式

3.3.1、根据id获取

由于 id 属性是 bean 的唯一标识，所以根据 bean 标签的 id 属性可以精确获取到一个组件对象；但也存在类型转换问题，具体见上一小节。
3.3.2、根据类型获取（最常用）

如图所示，根据类型获取bean，则不存在类型转换问题

1.     @Test    public void testHelloWord(){<?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">
6.    
7.     <bean id="helloWord" ></bean>
9. </beans>//获取IOC容器<?xml version="1.0" encoding="UTF-8"?>
10. <beans xmlns="http://www.springframework.org/schema/beans"
11.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
12.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
14.    
15.     <bean id="helloWord" ></bean>
17. </beans>ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");<?xml version="1.0" encoding="UTF-8"?>
18. <beans xmlns="http://www.springframework.org/schema/beans"
19.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
20.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
22.    
23.     <bean id="helloWord" ></bean>
25. </beans>//获取IOC容器中的bean<?xml version="1.0" encoding="UTF-8"?>
26. <beans xmlns="http://www.springframework.org/schema/beans"
27.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
28.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.    
31.     <bean id="helloWord" ></bean>
33. </beans>HelloWord helloWord = applicationContext.getBean(HelloWord.class);<?xml version="1.0" encoding="UTF-8"?>
34. <beans xmlns="http://www.springframework.org/schema/beans"
35.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
36.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
38.    
39.     <bean id="helloWord" ></bean>
41. </beans>helloWord.sayHello();    }

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注意：如下图所示，当根据类型获取bean时，要求IOC容器中指定类型的bean有且只能有一个；否则会报错

1. org.springframework.beans.factory.NoUniqueBeanDefinitionException:
2. No qualifying bean of type 'org.rain.spring.component.HelloWord' available:
3. expected single matching bean but found 2: helloWord,helloWordtwo

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3.3.3、根据id和类型获取

1.     @Test    public void testHelloWord(){<?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">
6.    
7.     <bean id="helloWord" ></bean>
9. </beans>//获取IOC容器<?xml version="1.0" encoding="UTF-8"?>
10. <beans xmlns="http://www.springframework.org/schema/beans"
11.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
12.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
14.    
15.     <bean id="helloWord" ></bean>
17. </beans>ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");<?xml version="1.0" encoding="UTF-8"?>
18. <beans xmlns="http://www.springframework.org/schema/beans"
19.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
20.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
22.    
23.     <bean id="helloWord" ></bean>
25. </beans>//获取IOC容器中的bean<?xml version="1.0" encoding="UTF-8"?>
26. <beans xmlns="http://www.springframework.org/schema/beans"
27.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
28.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.    
31.     <bean id="helloWord" ></bean>
33. </beans>HelloWord helloWord = applicationContext.getBean("helloWord",HelloWord.class);<?xml version="1.0" encoding="UTF-8"?>
34. <beans xmlns="http://www.springframework.org/schema/beans"
35.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
36.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
38.    
39.     <bean id="helloWord" ></bean>
41. </beans>helloWord.sayHello();    }

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3.3.4、重要扩展

如果组件类实现了接口，则根据接口类型可以获取 bean，前提是IOC容器中实现该接口的组件类型的bean有且只能有一个

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+++++++++++++++++++++++++++++++++++分割线+++++++++++++++++++++++++++++++++++

+++++++++++++++++++++++++++++++++++分割线+++++++++++++++++++++++++++++++++++

1.     @Test    public void testHelloWord(){<?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">
6.    
7.     <bean id="helloWord" ></bean>
9. </beans>//获取IOC容器<?xml version="1.0" encoding="UTF-8"?>
10. <beans xmlns="http://www.springframework.org/schema/beans"
11.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
12.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
14.    
15.     <bean id="helloWord" ></bean>
17. </beans>ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");<?xml version="1.0" encoding="UTF-8"?>
18. <beans xmlns="http://www.springframework.org/schema/beans"
19.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
20.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
22.    
23.     <bean id="helloWord" ></bean>
25. </beans>//根据接口类型获取IOC容器中的bean<?xml version="1.0" encoding="UTF-8"?>
26. <beans xmlns="http://www.springframework.org/schema/beans"
27.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
28.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
30.    
31.     <bean id="helloWord" ></bean>
33. </beans>HelloWord helloWord = (HelloWord) applicationContext.getBean(Hello.class);<?xml version="1.0" encoding="UTF-8"?>
34. <beans xmlns="http://www.springframework.org/schema/beans"
35.        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
36.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
38.    
39.     <bean id="helloWord" ></bean>
41. </beans>helloWord.sayHello();    }

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