4.spring 依赖注入的三种方式

Spring依赖注入的方式（3种）：

1.属性注入：是通过setter方法注入Bean的属性值或依赖的对象(使用多）
方法：<property name=" " value=" " ref=" ">

<bean id="userInfo" class="com.UserInfo" scope="singleton">
<property name="userName" value="悟空"></property>
<property name="userId" value="1001"></property>
<property name="department" ref="department"></propety>
</bean>

2.构造器注入：是通过构造方法注入Bean的属性值或依赖的对象（使用少）：是通过构造方法注入Bean的属性值或依赖的对象
第一步：在类中需要生成构造方法
第二步：在bean.xml中
<!--部门的bean 构造方法注入-->

方法:<constructor-arg>

1.按索引下标匹配参数
<!--按索引下标来匹配参数>
<bean id="department" class="com.Department">
<constructor-arg index="0" value="102"/>
<constructor-arg index="1" value="技术部"/>
</bean>
2.按参数类型匹配参数
<!--按参数类型配置参数-->
<bean id="userInfo" class="com.UserInfo">
<constructor-arg value="1002" type="java.lang.Integer"/>
<constructor-arg value="八戒" type="java.lang.String"/>
<constructor-arg value="department" type="com.Department"/>
</bean>

3.接口（工厂方法注入）（极少使用）

实例1：属性注入

1.结构目录：

代码：

Department.java

package com;public class Department {private Integer deId;private String deName;public void setDeId(Integer deId) {this.deId = deId;}public void setDeName(String deName) {this.deName = deName;}@Overridepublic String toString() {return "Department [deId=" + deId + ", deName=" + deName + "]";}}

UserInfo.java

package com;public class UserInfo {private Integer userId;private String userName;private Department department;public void setUserId(Integer userId) {this.userId = userId;}public void setUserName(String userName) {this.userName = userName;}public void getUserName() {System.out.println("姓名1:"+userName);}public void setDepartment(Department department) {this.department = department;}@Overridepublic String toString() {return "UserInfo [userId=" + userId + ", userName=" + userName + ", department=" + department + "]";}}

Test.java

package test;import org.springframework.beans.factory.BeanFactory;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.UserInfo;public class Test {public static void main(String[] args) {BeanFactory bf=new ClassPathXmlApplicationContext("beans.xml");UserInfo user=(UserInfo)bf.getBean("userInfo");System.out.print(user);//UserInfo [userId=1, userName=悟空, department=Department [deId=101, deName=技术部]]user.getUserName();//姓名1：悟空}}

beans.java

<?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-3.0.xsd"><!-- 部门的bean --> <bean id="department" class="com.Department"><property name="deId" value="101"></property><property name="deName" value="技术部"></property></bean><!-- UserInfo的bean --><!--UserInfo userInfo=new UserInfo(); userInfo.setUserName("悟空");-->   <bean id="userInfo" class="com.UserInfo">       <property name="userId" value="001"/><!-- 属性值注入 -->       <property name="userName" value="悟空"/><!-- 属性值注入 -->       <property name="department" ref="department"></property><!-- 对象注入 -->   </bean></beans>

打印结果：

UserInfo [userId=1, userName=悟空, department=Department [deId=101, deName=技术部]]姓名1:悟空

实例2：构造器注入

1.结构目录

2.代码

Department.java

package com;public class Department {private Integer deId;private String deName;public void setDeId(Integer deId) {this.deId = deId;}public void setDeName(String deName) {this.deName = deName;}//构造方法，无参和有参public Department() {};public Department(Integer deId, String deName) {super();this.deId = deId;this.deName = deName;}@Overridepublic String toString() {return "Department [deId=" + deId + ", deName=" + deName + "]";}}

Test.java

package test;import org.springframework.beans.factory.BeanFactory;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.Department;public class Test {public static void main(String[] args) {BeanFactory bf=new ClassPathXmlApplicationContext("beans.xml");Department de=(Department)bf.getBean("department");System.out.print(de);}}

beans.xml

<?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-3.0.xsd"><!-- 部门的bean --><!-- 1.按索引下标匹配参数 --><!--  <bean id="department" class="com.Department"><constructor-arg index="0" value="101"/><constructor-arg index="1" value="研发部"/></bean> --> <!-- 2.按参数类型匹配参数  --><bean id="department" class="com.Department"><constructor-arg value="八戒" type="java.lang.String"></constructor-arg><constructor-arg value="110" type="java.lang.Integer"></constructor-arg></bean></beans>

打印结果：

Department [deId=110, deName=八戒]