4、Spring之依赖注入
依赖注入就是对类的属性进行赋值4.1、环境搭建
创建名为spring_ioc_xml的新module，过程参考3.1节
4.1.1、创建spring配置文件
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727223106745-1071313988.png
4.1.2、创建学生类Student
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727223544516-1576170602.png
package org.rain.spring.pojo;
/**
* @author liaojy
* @date 2023/7/27 - 22:33
*/
public class Student {
private Integer id;
private String name;
private Integer age;
private String sex;
public Student() {
}
public Student(Integer id, String name, Integer age, String sex) {
this.id = id;
this.name = name;
this.age = age;
this.sex = sex;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
'}';
}
}4.2、setter注入(常用)
4.2.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727224149505-1555517654.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>4.2.2、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727224652242-1447672697.png
package org.rain.spring.test;
import org.junit.Test;
import org.rain.spring.pojo.Student;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* @author liaojy
* @date 2023/7/27 - 22:43
*/
public class IOCByXmlTest {
@Test
public void testDISetter(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("student", Student.class);
System.out.println(student);
}
}4.3、构造器注入
4.3.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727230908737-1049003748.png
注意：constructor-arg标签的数量，必须和某一个构造器方法的参数数量一致
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>4.3.2、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727231224737-1367593127.png
@Test
public void testDIConstructor(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentTwo", Student.class);
System.out.println(student);
}4.4、特殊值处理
4.4.1、null值
4.4.1.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727233826069-39727969.png
注意：该写法，实际为sex所赋的值是字符串null
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 4.4.1.2、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727234252929-444823133.png
由控制台日志可知，此时sex的值为null
@Test
public void testDIspecial(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentThree", Student.class);
System.out.println(student.getSex().toString());
}+++++++++++++++++++++++++++++++++++分割线+++++++++++++++++++++++++++++++++++
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727234522221-878704466.png
由控制台日志可知，此时age的值也为null；所以不配置属性也能实现同样的效果
4.4.2、xml字符值
4.4.2.1、方式一：实体
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727235244591-1748411546.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 4.4.2.2、方式二：CDATA节
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727235922458-1699878902.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> ]]> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.4.2.3、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230727235443719-1314532028.png
4.5、为类类型的属性赋值
4.5.1、方式一：外部bean（常用）
4.5.1.1、创建班级类Clazz
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728075604572-1664819856.png
package org.rain.spring.pojo;
/**
* @author liaojy
* @date 2023/7/28 - 7:54
*/
public class Clazz {
private Integer cid;
private String cname;
public Clazz() {
}
public Clazz(Integer cid, String cname) {
this.cid = cid;
this.cname = cname;
}
public Integer getCid() {
return cid;
}
public void setCid(Integer cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
@Override
public String toString() {
return "Clazz{" +
"cid=" + cid +
", cname='" + cname + '\'' +
'}';
}
}4.5.1.2、修改Student类
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728075827262-531578210.png
package org.rain.spring.pojo;
/**
* @author liaojy
* @date 2023/7/27 - 22:33
*/
public class Student {
private Integer id;
private String name;
private Integer age;
private String sex;
private Clazz clazz;
public Student() {
}
public Student(Integer id, String name, Integer age, String sex, Clazz clazz) {
this.id = id;
this.name = name;
this.age = age;
this.sex = sex;
this.clazz = clazz;
}
public Clazz getClazz() {
return clazz;
}
public void setClazz(Clazz clazz) {
this.clazz = clazz;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
", clazz=" + clazz +
'}';
}
}4.5.1.3、配置外部bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728080058951-1401742940.png
<bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean>4.5.1.4、引用外部bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728080415642-1274569692.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 4.5.1.5、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728080801637-1148768391.png
@Test
public void testDIOuterBean(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentfour", Student.class);
System.out.println(student);
}4.5.2、方式二、级联
4.5.2.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728081711151-1727163715.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 4.5.2.2、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728081934510-2077511813.png
@Test
public void testDICascade(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentFive", Student.class);
System.out.println(student);
}4.5.3、内部bean（常用）
4.5.3.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728082717723-1559136574.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.5.3.2、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230728083011141-667003247.png
@Test
public void testDIInnerBean(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentSix", Student.class);
System.out.println(student);
}4.6、为数组类型的属性赋值
4.6.1、修改Student类
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730005509496-1991526037.png
在Student类中添加或修改以下代码：
private String hobby[];
public String[] getHobby() {
return hobby;
}
public void setHobby(String[] hobby) {
this.hobby = hobby;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
", clazz=" + clazz +
", hobby=" + Arrays.toString(hobby) +
'}';
}4.6.2、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730010712574-1075875814.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>游泳 跑步 骑车 <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean>4.6.3、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730011028063-1857759415.png
@Test
public void testDIArray(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentSeven", Student.class);
System.out.println(student);
}4.7、为List集合类型的属性赋值
4.7.1、修改Clazz类
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730103943200-941860391.png
在Clazzt类中添加或修改以下代码：
private List<Student> students;
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}
@Override
public String toString() {
return "Clazz{" +
"cid=" + cid +
", cname='" + cname + '\'' +
", students=" + students +
'}';
}4.7.2、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730104408366-1914834324.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> ]]>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.7.3、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730104829397-881874794.png
@Test
public void testDIList(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Clazz clazz = applicationContext.getBean("clazzTwo", Clazz.class);
System.out.println(clazz);
}4.8、为Map集合类型的属性赋值
4.8.1、创建教师类Teacher
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730121302228-218473829.png
package org.rain.spring.pojo;
/**
* @author liaojy
* @date 2023/7/30 - 12:10
*/
public class Teacher {
private Integer tid;
private String tname;
public Teacher() {
}
public Teacher(Integer tid, String tname) {
this.tid = tid;
this.tname = tname;
}
public Integer getTid() {
return tid;
}
public void setTid(Integer tid) {
this.tid = tid;
}
public String getTname() {
return tname;
}
public void setTname(String tname) {
this.tname = tname;
}
@Override
public String toString() {
return "Teacher{" +
"tid=" + tid +
", tname='" + tname + '\'' +
'}';
}
}4.8.2、修改Student类
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730121531026-689655198.png
在Student类中添加或修改以下代码：
private Map<String,Teacher> teacherMap;
public Map<String, Teacher> getTeacherMap() {
return teacherMap;
}
public void setTeacherMap(Map<String, Teacher> teacherMap) {
this.teacherMap = teacherMap;
}
@Override
public String toString() {
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", sex='" + sex + '\'' +
", clazz=" + clazz +
", hobby=" + Arrays.toString(hobby) +
", teacherMap=" + teacherMap +
'}';
}4.8.3、配置bean
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730122303005-1589145909.png
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 游泳 跑步 骑车
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.8.4、测试
https://img2023.cnblogs.com/blog/2052479/202307/2052479-20230730122452654-2034967750.png
@Test
public void testDIMap(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentEight", Student.class);
System.out.println(student);
}4.9、为集合类型的属性赋值(解耦引用方式)
4.9.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802004438384-196089121.png
注意：使用util:list、util:map标签必须引入相应的XML命名空间
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean>
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 游泳 跑步 骑车 <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.9.2、测试
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802004856325-698101582.png
@Test
public void testDIUtil(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentNine", Student.class);
System.out.println(student);
}4.10、p命名空间(了解)
4.10.1、配置bean
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802010558080-1185539685.png
注意：p命名空间的依赖注入，本质上是属性方式（setter方法）的依赖注入
<bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> 4.10.2、测试
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802011011943-868187066.png
@Test
public void testDIP(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml");
Student student = applicationContext.getBean("studentTen", Student.class);
System.out.println(student);
}4.11、引入外部属性文件
4.11.1、引入数据库相关依赖
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802081328742-1012085585.png
<bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> mysql mysql-connector-java 5.1.49 <bean id="clazz" >
<property name="cid" value="1111"></property>
<property name="cname" value="三年E班"></property>
</bean> com.alibaba druid 1.0.31 4.11.2、创建外部属性文件
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802081544726-1516241646.png
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8
jdbc.username=root
jdbc.password=root4.11.3、配置bean
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802082412836-444822415.png
注意：使用context:property-placeholder标签必须引入相应的XML命名空间
<bean id="student" >
<property name="id" value="0011"></property>
<property name="name" value="张三"></property>
<property name="age" value="23"></property>
<property name="sex" value="男"></property>
</bean> 4.11.4、测试
https://img2023.cnblogs.com/blog/2052479/202308/2052479-20230802083658947-654932083.png
@Test
public void testDIOuterFile() throws SQLException {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-datasource");
DruidDataSource datasource = applicationContext.getBean("datasource", DruidDataSource.class);
System.out.println(datasource.getConnection());
}
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