Java框架spring 学习笔记（八）：注入对象类型属性

使用set方法注入对象属性

编写UserDao.java文件

package com.example.spring;

public class UserDao {
    public void print(){
        System.out.println("Dao print.");
    }
}

 

编写UserService.java文件

package com.example.spring;

public class UserService {
    //1、定义dao类型属性
    private UserDao userDao;
    //2、生成set方法
    public void setUserDao(UserDao userDao){
        this.userDao = userDao;
    }

    public void print(){
        System.out.println("Service print.");
        //如果不使用Spring对象属性注入的方式，想在service中调用dao里面的方法，必须先new一个dao的对象
        //UserDao dao = new UserDao();
        //dao.print();
        userDao.print();
    }
}

 

编写Beans.xml文件

<?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">

    <bean id="userDao" class="com.example.spring.UserDao"></bean>

    <bean id="userService" class="com.example.spring.UserService" >
        <property name="userDao" ref="userDao"></property>
    </bean>
</beans>

注意注入的属性是UserDao类的id。

 

编写Application.java

package com.example.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Application {
    public static void main(String[] args) {
        //bean配置文件所在位置 D:\\IdeaProjects\\spring\\src\\Beans.xml
        //使用AbstractApplicationContext容器
        AbstractApplicationContext context = new ClassPathXmlApplicationContext("file:D:\\IdeaProjects\\spring\\src\\Beans.xml");
        //得到配置创建的对象
        UserService userService = (UserService) context.getBean("userService");
        userService.print();
    }
}

 

运行输出

Service print.
Dao print.