springIOC : @PostConstruct and @PreDestroy

@PostConstruct and @PreDestroy

In this article, we show you how to use annotation @PostConstruct and @PreDestroy to do the same thing as init() and destroy() (Life cycle methods).

A HelloWorld bean with @PostConstruct and @PreDestroy annotation

HelloWorld.java

===========

package myspring;

import javax.annotation.PostConstruct;

import javax.annotation.PreDestroy;

public class HelloWorld {

    private String message;

   

    @PostConstruct

   public void init(){   

        System.out.println("Init Method");

    }

    public String getMessage() {

        return message;

    }

    public void setMessage(String message) {

        this.message = message;

    }

    @PreDestroy

    public void destroy(){

        System.out.println("destroy Method");

    }

}

By default, Spring will not aware of the @PostConstruct and @PreDestroy annotation. To enable it, you have to either register ‘CommonAnnotationBeanPostProcessor‘ or specify the ‘<context:annotation-config />‘ in bean configuration file,

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: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-4.0.xsd">

    <!-- <context:annotation-config /> -->

    <bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" />

    <!--<bean id="helloWorld" class="myspring.HelloWorld" init-method="init" destroy-method="destroy" >    -->

        <bean id="helloWorld" class="myspring.HelloWorld" >   

        <property name="message" value="Hi Hello World, how are you? " > </property>

    </bean>

</beans>

Test.java

=======

package myspring;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.AbstractApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

      public static void main(String[] args) {

         // AbstractApplicationContext context1 = new ClassPathXmlApplicationContext("Beans.xml");

                   ConfigurableApplicationContext context =

            new ClassPathXmlApplicationContext(new String[] {"Beans.xml"});

               

          HelloWorld helloWorld = (HelloWorld)context.getBean("helloWorld");

         

          System.out.println(helloWorld.getMessage());

                     //context.registerShutdownHook();

          context.close();

         //if we comment above line it will not call destroy() method.

    }

}