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