Spring InitializingBean and DisposableBean example

In Spring, InitializingBean and DisposableBean are two marker interfaces, a useful way for Spring to perform certain actions upon bean initialization and destruction.

• For bean implemented InitializingBean, it will run afterPropertiesSet() after all bean properties have been set.
• For bean implemented DisposableBean, it will run destroy() after Spring container is released the bean.

Example

Here’s an example to show you how to use InitializingBean and DisposableBean. A CustomerService bean to implement both InitializingBean and DisposableBean interface, and has a message property.

package com.mkyong.customer.services;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

public class CustomerService implements InitializingBean, DisposableBean
{
	String message;
	
	public String getMessage() {
	  return message;
	}

	public void setMessage(String message) {
	  this.message = message;
	}
	
	public void afterPropertiesSet() throws Exception {
	  System.out.println("Init method after properties are set : " + message);
	}
	
	public void destroy() throws Exception {
	  System.out.println("Spring Container is destroy! Customer clean up");
	}
	
}

File : Spring-Customer.xml

<beans 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">

       <bean id="customerService" class="com.mkyong.customer.services.CustomerService">
		<property name="message" value="i'm property message" />
       </bean>
		
</beans>

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();
    }
}

The ConfigurableApplicationContext.close() will close the application context, releasing all resources and destroying all cached singleton beans. It’s use for destroy() method demo purpose only 😃

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 afterPropertiesSet() method is called, after the message property is set; while the destroy() method is call after the context.close();

Thoughts…

I would not recommend to use InitializingBean and DisposableBean interface, because it will tight coupled your code to Spring. A better approach should be specifying the init-method and destroy-method attributes in your bean configuration file.