Spring Autowiring @Qualifier

There may be a situation when you create more than one bean of the same type and want to wire only one of them with a property, in such case you can use @Qualifier annotation along with @Autowired to remove the confusion by specifying which exact bean will be wired.

Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [spring.core.qualifier.PastInformation] is defined: expected single matching bean but found 2: two,one at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:970) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480) ... 15 more

<?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-4.0.xsd"

       default-autowire="byName" default-autowire-candidates="*">

       <context:annotation-config />

       <bean id="employee" class="spring.core.qualifier.Employee">

              <property name="id" value="1"></property>

              <property name="name" value="Rajesh kumar"></property>

              <property name="profile" value="developer"></property>

       </bean>

       <bean id="two" class="spring.core.qualifier.PastInformation">

              <property name="lastCompany" value="ABC2"></property>

       </bean>

      

       <bean id="one" class="spring.core.qualifier.PastInformation">

              <property name="lastCompany" value="ABC1"></property>

       </bean>

</beans>

package spring.core.qualifier;

public class PastInformation {

      

       private String lastCompany;

       public void displayInfo(String seq) {

             

              String empDetails = seq + " : "+lastCompany;

              System.out.println(empDetails);

             

       }

       /* setters and getters */

}

package spring.core.qualifier;

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

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

public class Employee {

       @Autowired

       @Qualifier("one")

       private PastInformation lastOne;

       @Autowired

       @Qualifier("two")

       private PastInformation lastSecond;

       private int id;

       private String name;

       private String profile;

       public void displayInfo() {

              lastOne.displayInfo("first");

              lastSecond.displayInfo("last");

              String empDetails = "id : "+id+" name :"+name+" profile : " + profile;

              System.out.println(empDetails);

       }

    /* setters and getters */

}

package spring.core.qualifier;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestIOC {

       private static ApplicationContext appContext;

       public static void main(String[] args) {

              appContext = new ClassPathXmlApplicationContext     

                           ("spring/core/qualifier/autowiring-spring.xml");

              Employee empl1 = appContext.getBean("employee", Employee.class);

              empl1.displayInfo();

       }

}

Output:

first: ABC1

last: ABC2

id: 1 name : Rajesh kumar profile: developer