Spring深入浅出（十），注解，@Qualifier

可能会有这样一种情况，当你创建多个具有相同类型的 bean 时，并且想要用一个属性只为它们其中的一个进行装配，在这种情况下，你可以使用 @Qualifier 注释和 @Autowired 注释通过指定哪一个真正的 bean 将会被装配来消除混乱。

一、创建实体Bean

package com.clzhang.spring.demo;

public class Student {
    private Integer age;
    private String name;

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getAge() {
        return age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

二、创建业务逻辑层

package com.clzhang.spring.demo;

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

public class Profile {
    @Autowired
    @Qualifier("student2")
    private Student student;

    public Profile() {
        System.out.println("Inside Profile constructor.");
    }

    public void printAge() {
        System.out.println("Age : " + student.getAge());
    }

    public void printName() {
        System.out.println("Name : " + student.getName());
    }
}

三、创建主程序

package com.clzhang.spring.demo;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
      Profile profile = (Profile) context.getBean("profile");
      profile.printAge();
      profile.printName();
   }
}

四、配置文件如下

<?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-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

   <context:annotation-config/>

   <!-- Definition for profile bean -->
   <bean id="profile" class="com.clzhang.spring.demo.Profile">
   </bean>

   <!-- Definition for student1 bean -->
   <bean id="student1" class="com.clzhang.spring.demo.Student">
      <property name="name"  value="Zara" />
      <property name="age"  value="11"/>
   </bean>

   <!-- Definition for student2 bean -->
   <bean id="student2" class="com.clzhang.spring.demo.Student">
      <property name="name"  value="Nuha" />
      <property name="age"  value="2"/>
   </bean>

</beans>

五、运行

Inside Profile constructor.
Age : 2
Name : Nuha

本文参考：

https://www.w3cschool.cn/wkspring/knqr1mm2.html