Spring_spring自动装配置注解(@Autowired)指定要装配置的参数(@Qualifier)

@Autowired
  a>默认按类型by type
  b>如果想用byName,使用Qulifler
  c>写在private field(第三种注入形式)(不建议,破封装)
  d>如果写在set上,@qualifier需要写在参数上

导入spring注解配置

xmlns:context="http://www.springframework.org/schema/context

​​http://www.springframework.org/schema/context​​

​​http://www.springframework.org/schema/context/spring-context.xsd">​​

<?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.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context.xsd">

  <context:annotation-config />
  <bean id="userDaoImpl" class="com.bjsxd.dao.impl.UserDaoImpl">
  </bean>
  <bean id="userDaoImpl2" class="com.bjsxd.dao.impl.UserDaoImpl">
  </bean>

  <bean id="userService" class="com.bjsxd.service.UserService">
  
  </bean>
</beans>

package com.bjsxd.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.bjsxd.dao.UserDao;
import com.bjsxd.model.User;

public class UserService {
  private UserDao userDao;

  public UserDao getUserDao() {
    return userDao;
  }

  @Autowired//自动装配
  public void setUserDao(@Qualifier("userDaoImpl")UserDao userDao) {//指定要使用的的bean的ID注入
    this.userDao = userDao;
  }

  public void add(User user) {
    userDao.save(user);
  }
}