一、實現(xiàn)過程

（1）在service里面把dao作為類屬性

（2）生成dao類型屬性的set方法

（3）在配置文件完成注入關(guān)系

image.png

二、代碼

service層 UserService.java

package work.zhangdoudou.service;

import work.zhangdoudou.dao.UserDao;

public class UserService {
    //1定義一個dao類型的屬性
    private UserDao userDao;
    //2生成set方法
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }
    
    public void add(){  
        System.out.println("service-------");
        
        //在service里面調(diào)用dao類對象，才能調(diào)用dao里面的方法
        userDao.add();
    }
    
}

dao層 UserDao.java

package work.zhangdoudou.dao;

public class UserDao {
    public void add(){
        System.out.println("dao--------");
    }
}

配置文件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-3.0.xsd">
   
    <!-- 注入對象類型屬性 -->
    <!-- 配置service和dao對象 -->
    <bean id="userDao" class="work.zhangdoudou.dao.UserDao"></bean>
    <bean id="userService" class="work.zhangdoudou.service.UserService">
        <!-- 注入dao對象，不寫value屬性，現(xiàn)在是對象寫ref 
            name:寫service類里面屬性名稱
            ref:寫dao配置的id名稱
        -->
        <property name="userDao" ref="userDao"></property>
    </bean>
   
</beans>

測試類TestUser.java

package work.zhangdoudou.test;

import static org.junit.Assert.*;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import work.zhangdoudou.service.UserService;

public class TestUser {

    @Test
    public void test() {
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        UserService userService= (UserService)context.getBean("userService");
        userService.add();
    }
}

三、運行結(jié)果

image.png