用@Repository、@Service 和 @Constroller,代替@Component,知名见意,知道是哪一层,@Autowired代替@Resource。

源码获取github

1.@Repository、@Service 和 @Constroller代替@Component

  • @Repository:持久化层、数据访问层、也就是dao层,写在这上面,功能跟@Component,只是为了知名见意
  • @Service:写在Service层
  • @Controller:写在控制层,也就是SpringMvc那层

2.@Autowired代替@Resource

  • @Autowired是Spring自己的,@Resource不是Spring的
  • 面试题:@Resource和@Autowired的区别:
    • @Resource先按名称再按照类型查找
    • @Autowired先按类型再按照名称查找

3.项目结构(jar包一样)

4.核心配置文件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" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd">
   <!--1.启动Spring注解-->
   <context:annotation-config></context:annotation-config>
   <!--2.扫描-->
   <context:component-scan base-package="com.hs"/>

</beans>

5.dao层

UserDao.java

package com.hs.dao;

public interface UserDao {
   void add();
}

UserDaoImpl.java

package com.hs.dao.impl;

import com.hs.dao.UserDao;
import org.springframework.stereotype.Repository;

//@Component//(value = "userDao") //相当于<bean id="userDaoImpl" class="com.hs.dao.impl.UserDaoImpl"/>
@Repository //跟上面意思一样,只是为了知名见意
public class UserDaoImpl implements UserDao {

   @Override
   public void add() {
      System.out.println("UserDao层的实现类--->ADD");
   }
}

6.Service层

UserService.java

package com.hs.service;

public interface UserService {

   void add();
}

UserServiceImpl.java

package com.hs.service.impl;

import com.hs.dao.UserDao;
import com.hs.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Service;

//@Component //相当于<bean id="userServiceImpl" class="com.hs.service.impl.UserServiceImpl">
@Service    //跟上面意思一样,只是为了知名见意
public class UserServiceImpl implements UserService {

   private UserDao userDao;

   public UserDao getUserDao() {
      return userDao;
   }

   //面试题:Resource和Autowired的区别
   //@Resource先按名称再按照类型查找
   //@Autowired先按类型再按照名称查找
   @Autowired
   //指明id名字
   @Qualifier(value = "userDaoImpl")
   public void setUserDao(UserDao userDao) {
      this.userDao = userDao;
   }

   @Override
   public void add() {
      System.out.println("UserService层的实现类--->ADD");
      this.userDao.add();
   }
}

7.Controller层

UserController.java

package com.hs.web;

import com.hs.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

//@Component //相当于<bean id="userController" class="com.hs.web.UserController"/>
@Controller //跟上面意思一样,只是为了知名见意
public class UserController {

   @Autowired
   private UserService userService;

   public UserService getUserService() {
      return userService;
   }

   public void add() {
      System.out.println("UserController层--->ADD");
      this.userService.add();
   }

}

8.测试

package com.hs.test;

import com.hs.web.UserController;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MethodTest {
   @Test
   public void test01() {
      ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans.xml");
      UserController controller = applicationContext.getBean("userController", UserController.class);
      controller.add();
   }
}

控制台输出:

UserController层—>ADD
UserService层的实现类—>ADD
UserDao层的实现类—>ADD