How to use InitializingBean and DisposableBean interface for initializing and destroying a bean in Spring Framework ?.

Program to demonstrate how to use InitializingBean and DisposableBean interface for initializing and destroying a bean in Spring Framework

Step 1 - Create a POJO class here its Employee.java having getters, setters, constructor and implementing two interfaces InitializingBean and DisposableBean, along with its unimplemented methods as afterPropertiesSet() and destroy()

package com.hubberspot.spring.InitDestroy;

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

// Create a POJO class Employee which implements
// two interfaces by name InitializingBean and DisposableBean
// these interfaces has two methods as : afterPropertiesSet() and 
// destroy(). 
public class Employee implements InitializingBean, DisposableBean{

 private String name;
 private int age;

 public Employee() {

 }

 public String getName() {
  return name;
 }

 public void setName(String name) {
  this.name = name;
 }

 public int getAge() {
  return age;
 }

 public void setAge(int age) {
  this.age = age;
 }

 // This method is called to provide some initialization to 
 // bean by Spring Framework container
 @Override
 public void afterPropertiesSet() throws Exception {  
  System.out.println("Initializing the Employee bean ...");  
 }

 // This method is called to destroy a bean  
 // by Spring Framework container
 @Override
 public void destroy() throws Exception {
  System.out.println("Destroying the Employee bean ...");
 }

}

Step 2 - Create a Spring Configuration file having beans


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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"
 xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans-3.1.xsd">


 <bean id="employee" class="com.hubberspot.spring.InitDestroy.Employee">

  <property name="name" value="Jonty" />
  <property name="age" value="28" />

 </bean>
</beans>


Step 3 - Create a test class here its Test.java having AbstractApplicationContext class for providing registerShutdownHook method to execute destroy method.

package com.hubberspot.spring.InitDestroy;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

 public static void main(String[] args) {

  // ApplicationContext is a Spring interface which 
  // provides with the configuration for an application. 
  // It provides us with all the methods that BeanFactory 
  // provides. It loads the file resources in a older 
  // and generic manner. It helps us to publish events to the
  // listener registered to it. It also provides quick support
  // for internationalization. It provides us with the object 
  // requested, it reads the configuration file and provides
  // us with the necessary object required.
  // We are using concrete implementation of ApplicationContext
  // here called as ClassPathXmlApplicationContext because this 
  // bean factory reads the xml file placed in the classpath of 
  // our application. We provide ClassPathXmlApplicationContext
  // with a configuration file called as spring.xml placed
  // at classpath of our application. 
  AbstractApplicationContext context = 
    new ClassPathXmlApplicationContext(("spring.xml"));

  // Using AbstractApplicationContext registerShutdownHook()
  // method to demonstrate destroy() method being called
  context.registerShutdownHook();

  // In order to get a object instantiated for a particular bean 
  // we call getBean() method of ClassPathXmlApplicationContext
  // passing it the id for which the object is to be needed. 
  // Here getBean() returns an Object. We need to cast it back 
  // to the Employee object. Without implementing new keyword we 
  // have injected object of Employee just by reading an xml 
  // configuration file.
  Employee employee = (Employee)context.getBean("employee");

  System.out.println("The name of Employee is : " + employee.getName());
  System.out.println("The age of Employee is : " + employee.getAge());

 }

}

Output of the program :