@Autowired注解使用

a) 默认按类型by type

b) 如果想用byName，使用@Qulifier

c) 写在private field（第三种注入形式）（不建议，破坏封装）

d) 如果写在set上，@qualifier需要写在参数上

 

<?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="u1" class="com.bjsxt.dao.impl.UserDAOImpl"/>
  <bean id="u2" class="com.bjsxt.dao.impl.UserDAOImpl"/>
  <bean id="userService" class="com.bjsxt.service.UserService" />
  </beans>

 

@Autowired
public void setUserDAO(@Qualifier("u1") UserDAO userDAO) {
           this.userDAO = userDAO;
}

 

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