JAVA EE: Event handling in spring [ContextStartedEvent and ContextStoppedEvent]

Sunday, 23 September 2018

Event handling in spring [ContextStartedEvent and ContextStoppedEvent] | Spring event handling

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Event handling in spring [ContextStartedEvent and ContextStoppedEvent] | Spring event handling

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;

/**

 * Spring bean

 *

 */

public class Employee

{

    private String name;

    public void setName(String name)

    {

        this.name = name;

    }

    public void employeeDetails()

    {

        System.out.println("Employee Name =  " + name);

    }

}

ContextStartEventHandler.java

package com.ram.eventhandler;

import org.springframework.context.ApplicationListener;

import org.springframework.context.event.ContextStartedEvent;

public class ContextStartEventHandler implements ApplicationListener<ContextStartedEvent>

{

    public void onApplicationEvent(ContextStartedEvent event)

    {

        System.out.println("ContextStartedEvent Received = "+ event);

    }

}

ContextStopEventHandler.java

package com.ram.eventhandler;

import org.springframework.context.ApplicationListener;

import org.springframework.context.event.ContextStoppedEvent;

public class ContextStopEventHandler implements ApplicationListener<ContextStoppedEvent>

{

    public void onApplicationEvent(ContextStoppedEvent event)

    {

        System.out.println("ContextStoppedEvent Received = "+event);

    }

}

applicationContext.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-4.3.xsd">

    <bean id="employee" class="com.ram.model.Employee">

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

    </bean>

    <bean id="contextStartEventHandler" class="com.ram.eventhandler.ContextStartEventHandler" />

    <bean id="contextStopEventHandler" class="com.ram.eventhandler.ContextStopEventHandler" />

</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");

        context.start();

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

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

        System.out.println(

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

        employee.employeeDetails();

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

        context.stop();

    }

}

Output

Aug 25, 2018 10:35:16 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@610694f1: startup date [Sat Aug 25 10:35:16 IST 2018]; root of context hierarchy

Aug 25, 2018 10:35:16 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

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

ContextStartedEvent Received = org.springframework.context.event.ContextStartedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@610694f1: startup date [Sat Aug 25 10:35:16 IST 2018]; root of context hierarchy]

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

Got employee object from the ApplicationContext(Spring Container)

Employee Name =  Peter

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

ContextStoppedEvent Received = org.springframework.context.event.ContextStoppedEvent[source=org.springframework.context.support.ClassPathXmlApplicationContext@610694f1: startup date [Sat Aug 25 10:35:16 IST 2018]; root of context hierarchy]