Spring注入方式（二、构造器注入）

与设值注入相似 ，只需改动一下两个文件

1.UserServiceImpl中代码添加构造方法：

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    //构造器注入
    public UserServiceImpl(UserDao userDao){
        this.userDao=userDao;
    }
//    //设值注入
//    public void setUserDao(UserDao userDao) {
//        this.userDao = userDao;
//    }

    @Override
    public void save(String arg) {
        System.out.println("userServiceImpl接受参数："+arg);
        arg=arg+":"+this.hashCode();
        userDao.save(arg);
    }
}

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2.修改Bean.xml 改为构造注入

<?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">

<!--    <bean id="userService" class="test.UserServiceImpl">-->
<!--        <property name="userDao" ref="userDao"/>-->
<!--    </bean>-->
    <bean id="userDao" class="test.UserDaoImpl"></bean>
    <bean id="userService" class="test.UserServiceImpl">
        <constructor-arg name="userDao" ref="userDao"/>
    </bean>
</beans>

View Code

3.其他代码不动，TestMain运行结果：