案例:
UserService.java
package com.xdr.ioc;
public interface UserService {
public void say();
}
UserServiceImpl.java
package com.xdr.ioc;
public class UserServiceImpl implements UserService{
//声明UserDao属性
private UserDao userDao;
//添加UserDao属性的setter方法,用于实现依赖注入
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
//实现接口中的方法
@Override
public void say() {
// TODO Auto-generated method stub
//调用userDao中的say()方法,并执行输出语句
this.userDao.say();
System.out.println("userService say hello world!");
}
}
applicationContext.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.xsd">
<!-- 将制定类配置给spring,让spring创建其对象实例 -->
<bean id="userDao" class="com.xdr.ioc.UserDaoImpl"></bean>
<!-- 添加一个id为userService的实例 -->
<bean id="userService" class="com.xdr.ioc.UserServiceImpl">
<!-- 将id为userDao的Bean实例注入到userService实例中 -->
<property name="userDao" ref="userDao"></property>
</bean>
</beans>
测试类:TestDI.java
package com.xdr.ioc;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestDI {
public static void main(String[] args) {
//1.初始化spring容器,加载配置文件
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
//2.通过容器获取UserService实例
UserService userService = (UserService) applicationContext.getBean("userService");
//3.调用实例中的say()方法
userService.say();
}
}
结果: