Spring Part 06 - @Qualifier

  Spring - Qualifier

Maven Dependency:

<dependency>

  <groupId>org.springframework</groupId>

  <artifactId>spring-context</artifactId>

  <version>5.3.16</version>

</dependency>

Sample Program for @Qualifier using 'Spring Framework' 

beans_di.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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

    <context:annotation-config/>

    <bean id="engineModel1" class="com.ah.di.Engine">
        <property name="engineModel" value="Model-1"/>
    </bean>

    <bean id="engineModel2" class="com.ah.di.Engine">
        <property name="engineModel" value="Model-2"/>
    </bean>

    <bean id="car" class="com.ah.di.Car" />

</beans>

package com.ah.di;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

    public static void main(String[] args) {

        ApplicationContext context =

                new ClassPathXmlApplicationContext("beans_di.xml");

        Car car = context.getBean("car",Car.class);
        car.checkCarEngine();
    }

}

package com.ah.di;

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

public class Car {

    @Autowired
    @Qualifier("engineModel2")
    private Engine engine;

    public void checkCarEngine(){
        if(engine!=null){
            engine.testEngine();
        }else{
            System.out.println("Engine is dead");
        }
    }
}

package com.ah.di;

public class Engine {

    public void testEngine(){
        System.out.println("engine is working" );
    }
}

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