Table of Contents
In this tutorial, we will see about @Qualifier Annotation in spring.
Tutorial Content: Spring tutorial for beginners
- Introduction to spring framework
- Spring interview questions
- Dependency injection(ioc) in spring
- Spring XML based configuration example
- Spring java based configuaration
- Dependency injection via setter method in spring
- Dependency injection via constructor in spring
- Spring Bean scopes with examples
- Initializing collections in spring
- Beans Autowiring in spring
- Inheritance in Spring
- Spring ApplicationContext
- Spring lifetime callbacks
- BeanPostProcessors in Spring
- Annotation based Configuration in spring
- Spring AOP tutorial
you can have more than one bean of same type in your XML configuration but you want to autowire only one of them ,so @Qualifier removes confusion created by @Autowired by declaring exactly which bean is to autowired.
@Qualifier Annotation in spring Example:
For configuring spring in your eclipse ide please refer hello world example
1.Country.java
This is simple pojo class having some attributes so here country has name and object of Capital class.
Create Country.java under package org.arpit.javapostsforlearning.Copy following content into Country.java.
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package org.arpit.javapostsforlearning; import org.springframework.beans.factory.annotation.Autowired; public class Country { String countryName; @Autowired @Qualifier("capitalA") Capital capital; public String getCountryName() { return countryName; } public void setCountryName(String countryName) { this.countryName = countryName; } public Capital getCapital() { return capital; } } |
2.Capital.java
This is also simple pojo class having one attribute called “capitalName”.
Create Capital.java under package org.arpit.javapostsforlearning.java.Above Country class contains object of this class.Copy following content into Capital.java
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package org.arpit.javapostsforlearning; public class Capital { String capitalName; public String getCapitalName() { return capitalName; } public void setCapitalName(String capitalName) { this.capitalName = capitalName; } } |
3.ApplicationContext.xml
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<?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/> <bean id="CountryBean" class="org.arpit.javapostsforlearning.Country"> <property name="countryName" value="India" /> </bean> <bean id="capitalA" class="org.arpit.javapostsforlearning.Capital"> <property name="capitalName" value="Delhi" /> </bean> <bean id="capitalB" class="org.arpit.javapostsforlearning.Capital"> <property name="capitalName" value="Mumbai" /> </bean> </beans> |
As you can note here we are having two beans of same type.In Country.java we have used @Qualifier(“capitalA”) it means we want to autowire capital property of country with bean id=”capitalA” in XML configuration file.
4.QualifierAnnotationInSpringMain.java
This class contains main function.Create QualifierAnnotationInSpringMain.java under package org.arpit.javapostsforlearning.Copy following content into QualifierAnnotationInSpringMain.java
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package org.arpit.javapostsforlearning; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class QualifierAnnotationInSpringMain{ public static void main(String[] args) { ApplicationContext appContext = new ClassPathXmlApplicationContext("ApplicationContext.xml"); Country countryObj = (Country) appContext.getBean("CountryBean"); String countryName=countryObj.getCountryName(); Capital capital=countryObj.getCapital(); String capitalName=capital.getCapitalName(); System.out.println(capitalName+" is capital of "+countryName); } } |
5.Run it
When you will run above application,you will get following as output.
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Delhi is capital of India |
That’s all about @Qualifier Annotation in spring.
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