Spring @PostConstruct And @PreDestroy Example

Posted on March 29, 2010 ,     Last modified : June 13, 2011

By mkyong

In Spring, you can either implements InitializingBean and DisposableBean interface or specify the init-method and destroy-method in bean configuration file for the initialization and destruction callback function. In this article, we show you how to use annotation @PostConstruct and @PreDestroy to do the same thing.

Note
The @PostConstruct and @PreDestroy annotation are not belong to Spring, it’s located in the J2ee library – common-annotations.jar.

@PostConstruct and @PreDestroy

A CustomerService bean with @PostConstruct and @PreDestroy annotation

package com.mkyong.customer.services;
 
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
 
public class CustomerService
{
 String message;
 
 public String getMessage() {
   return message;
 }
 
 public void setMessage(String message) {
   this.message = message;
 }
 
 @PostConstruct
 public void initIt() throws Exception {
   System.out.println("Init method after properties are set : " + message);
 }
 
 @PreDestroy
 public void cleanUp() throws Exception {
   System.out.println("Spring Container is destroy! Customer clean up");
 }
 
}

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

1. CommonAnnotationBeanPostProcessor

 xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
 
  class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" />
 
  id="customerService" class="com.mkyong.customer.services.CustomerService">
   name="message" value="i'm property message" />
 

 

2.

 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-2.5.xsd
 http://www.springframework.org/schema/context
 http://www.springframework.org/schema/context/spring-context-2.5.xsd">
 
  />
 
  id="customerService" class="com.mkyong.customer.services.CustomerService">
   name="message" value="i'm property message" />
 

 

Run it

package com.mkyong.common;
 
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
import com.mkyong.customer.services.CustomerService;
 
public class App 
{
    public static void main( String[] args )
    {
     ConfigurableApplicationContext context = 
       new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});
 
     CustomerService cust = (CustomerService)context.getBean("customerService");
 
     System.out.println(cust);
 
     context.close();
    }
}

Output

Init method after properties are set : im property message
com.mkyong.customer.services.CustomerService@47393f
...
INFO: Destroying singletons in org.springframework.beans.factory.
support.DefaultListableBeanFactory@77158a: 
defining beans [customerService]; root of factory hierarchy
Spring Container is destroy! Customer clean up

The initIt() method (@PostConstruct) is called, after the message property is set, and the cleanUp() method (@PreDestroy) is call after the context.close();