JAVA EE: Spring Bean Life Cycle - Spring init-method and destroy-method

Monday, 20 August 2018

Spring Bean Life Cycle - Spring init-method and destroy-method | Spring Tutorial

🚀 Enjoying Java & Spring Tutorials?

Subscribe to Ram N Java for beginner-friendly, hands-on programming guides!

What are init-method and destroy-method?

In Spring, beans often need to execute custom setup logic when they are created and custom cleanup logic when they are destroyed. You can configure custom callback methods declaratively in the Spring XML configuration file using the init-method and destroy-method attributes.

init-method: Specifies a custom method inside your bean class that the Spring Container calls immediately after the bean is instantiated and all its dependencies are injected.
destroy-method: Specifies a custom method called just before the container destroys the bean and releases its resources.

Why Use XML-Based Lifecycle Configuration?

Configuring lifecycle callbacks via XML offers distinct advantages for modular architecture:

Zero Code Coupling: Your Java class remains pure and independent of any Spring-specific interfaces (such as InitializingBean or DisposableBean).
Flexible Method Naming: You can choose descriptive method names like init(), setup(), cleanup(), or destroy().
Externalized Configuration: Lifecycle behaviors can be modified entirely through XML configuration files without recompiling Java source code.

XML Configuration Example

Here is how you define a bean with custom lifecycle methods in your Spring XML configuration file:

    <bean id="myBean" class="com.ram.MyBean" init-method="init" destroy-method="destroy" />
  

Related Tutorials from Ram N Java

Click here to watch on Youtube:
https://www.youtube.com/watch?v=wa2nphKki2I&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge:

Spring Bean Life Cycle - Spring init-method and destroy-method | Spring Tutorial

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0%20http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.2.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 dependencies -->

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-core</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-context</artifactId>

            <version>${spring.version}</version>

        </dependency>

    </dependencies>

</project>

Employee.java

package com.ram.model;

public class Employee

{

    private int id;

    private String name;

    public int getId()

    {

        return id;

    }

    public void setId(int id)

    {

        this.id = id;

    }

    public String getName()

    {

        return name;

    }

    public void setName(String name)

    {

        this.name = name;

    }

    public void init() throws Exception

    {

        System.out.println("inside Init method after properties are set. ");

    }

    public void cleanUp() throws Exception

    {

        System.out.println("Inside cleanUp(), Performed clean up tasks.");

    }

    @Override

    public String toString()

    {

        return "Employee [id=" + id + ", name=" + name + "]";

    }

}

applicationContext.xml

<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-4.3.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-4.3.xsd">

    <bean id="employee" class="com.ram.model.Employee" init-method="init"

        destroy-method="cleanUp">

        <property name="id" value="100"></property>

        <property name="name" value="Peter"></property>

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ConfigurableApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.model.Employee;

public class App

{

    public static void main(String[] args)

    {

        ConfigurableApplicationContext  context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        Employee employee = context.getBean("employee", Employee.class);

        System.out.println(

                "Got employee object from the ApplicationContext(Spring Container)");

        System.out.println(employee);

        context.close();

    }

}

Output

Aug 07, 2018 9:46:31 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Tue Aug 07 09:46:31 IST 2018]; root of context hierarchy

Aug 07, 2018 9:46:31 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

inside Init method after properties are set. 

---------------------------------------

Got employee object from the ApplicationContext(Spring Container)

Employee [id=100, name=Peter]

Aug 07, 2018 9:46:31 AM org.springframework.context.support.AbstractApplicationContext doClose

INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Tue Aug 07 09:46:31 IST 2018]; root of context hierarchy

Inside cleanUp(), Performed clean up tasks.