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About Byron Kiourtzoglou

Byron Kiourtzoglou
Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.

Declare bean in Spring container

With this example we are going to demonstrate how to declare a Bean in the Spring container. A Spring bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. In short, to declare a Class as a simple Spring Bean you should follow the steps below:

1. Include the following JARs in the classpath:

    – Spring framework libraries

  • org.springframework.asm-3.0.2.RELEASE.jar
  • org.springframework.beans-3.0.2.RELEASE.jarorg.springframework.context-3.0.2.RELEASE.jar
  • org.springframework.core-3.0.2.RELEASE.jar
  • org.springframework.expression-3.0.2.RELEASE.jar
  • – external libraries

  • commons.logging-1.1.1.jar

2. Create a simple Java class

The class HelloBean.java has a simple method, printHello().

package com.javacodegeeks.snippets.enterprise;

public class HelloBean {

	public void printHello() {
		System.out.println("Hello World!");
	}

}

3. Define the HelloBean.java class as a Spring bean, in Spring configuration file.

The bean is defined in spring-beans.xml file inside the <bean> element. It has two attributes, the bean id and the class that is the class of the bean.
spring-beans.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:p="http://www.springframework.org/schema/p"
  xmlns:context="http://www.springframework.org/schema/context"
  xmlns:jdbc="http://www.springframework.org/schema/jdbc"
  xmlns:tx="http://www.springframework.org/schema/tx"
  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">

    <bean id="helloBean" class="com.javacodegeeks.snippets.enterprise.HelloBean" />

</beans>

3. Run the application

In DeclareBeanInSpringContainer.java class we load the Spring configuration file, using the FileSystemXmlApplicationContext Class with the configuration file name. Using the getBean(String name) API method of ApplicationContext Class, we can get an instance of the helloBean and invoke its method.

package com.javacodegeeks.snippets.enterprise;

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

public class DeclareBeanInSpringContainer {

	public static void main(String[] args) throws Exception {

		ApplicationContext context = new FileSystemXmlApplicationContext("spring-beans.xml");

		HelloBean helloBean = (HelloBean) context.getBean("helloBean");
		
		helloBean.printHello();

	}

}

4. Output

The output is shown below:
Output:

Hello World!

 
This was an example of how to declare a Bean in the Spring container.

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