Spring ---annotation (重点)--AutoWired 不常用

1. 默认按类型 by type, 如果想用byname, 使用@Qualifier

2. 如果写在set上, @qualifier需要写在参数上

bean.xml:

默认bytype去找set方法, 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"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	<context:annotation-config />
  <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl">
  </bean>
  <bean id="userService" class="com.bjsxt.service.UserService" >
  </bean>
</beans>

在set方法上加入@AutoWired:

package com.bjsxt.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;
public class UserService {
	private UserDAO userDAO;
	public void init() {
		System.out.println("init");
	}
	public void add(User user) {
		userDAO.save(user);
	}
	public UserDAO getUserDAO() {
		return userDAO;
	}
	@Autowired
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
	public void destroy() {
		System.out.println("destroy");
	}
}

如果bytype找到2个bean , 参考下面的xml文件,可以在service文件里再加入@Qualifier标识符,

<?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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	<context:annotation-config />
  <bean id="u" class="com.bjsxt.dao.impl.UserDAOImpl">
  </bean>
  <bean id="u2" class="com.bjsxt.dao.impl.UserDAOImpl">
  </bean> 

  <bean id="userService" class="com.bjsxt.service.UserService" >

  </bean>

</beans>

UserService.java:

package com.bjsxt.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User;

public class UserService {
	private UserDAO userDAO;
	public void init() {
		System.out.println("init");
	}
	public void add(User user) {
		userDAO.save(user);
	}
	public UserDAO getUserDAO() {
		return userDAO;
	}
	@Autowired
	public void setUserDAO(@Qualifier("u") UserDAO userDAO) {
		this.userDAO = userDAO;
	}
	public void destroy() {
		System.out.println("destroy");
	}
}