Spring Timer Tasks

Timer is a utility class which is used to schedule tasks for both one time and repeated execution. Through timer tasks, Spring framework provide support for executing tasks which are scheduled to get executed periodically for multiple times or even single time also.

There are other ways to achieve scheduler functionality in java e.g. running thread in infinite loop, using executor service, or using 3rd party APIs like quartz. Timer just happens to be one of them.

In Spring, there are two ways to use timer tasks:

1. Configure MethodInvokingTimerTaskFactoryBean
2. Extend java.util.TimerTask

Lets demo usage of each one using example.

1. Configure MethodInvokingTimerTaskFactoryBean

In this method, timer task bean and method to be executed inside it, is configured in org.springframework.scheduling.timer.MethodInvokingTimerTaskFactoryBean definition. This is a factory bean which exposes a TimerTask object which delegates job execution to a specified (static or non-static) method. This avoids the need to implement a one-line TimerTask that just invokes an existing business method.

A sample spring configuration will look like this:

<beans>

    <bean id="demoTimerTask" class="com.howtodoinjava.task.DemoTimerTask"></bean>

    <bean id="timerTaskFactoryBean"	
    		class="org.springframework.scheduling.timer.MethodInvokingTimerTaskFactoryBean">
		<property name="targetObject" ref="demoTimerTask"></property>
		<property name="targetMethod" value="execute"></property>
	</bean>

    <bean id="scheduledTimerTask" class="org.springframework.scheduling.timer.ScheduledTimerTask">
		<property name="timerTask" ref="timerTaskFactoryBean"></property>
		<property name="period" value="5000"></property>
	</bean>

    <bean class="org.springframework.scheduling.timer.TimerFactoryBean">
		<property name="scheduledTimerTasks">
			<list>
				<ref local="scheduledTimerTask"></ref>
			</list>
		</property>
	</bean>
</beans>

Above timer task will get executed in every 5 seconds. Lets write out demo timer task and test it.

package com.howtodoinjava.task;

import java.util.Date;

/**
 * No need to implement any interface
 * */
public class DemoTimerTask {

	//Define the method to be called as configured
	public void execute()
	{
		System.out.println("Executed task on :: " + new Date());
	}
}

Now, lets test the timer task.

package com.howtodoinjava.timer;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestDemoTimerTask {
	public static void main(String[] args) {
		new ClassPathXmlApplicationContext("application-config.xml");
	}
}

Executed task on :: Mon Apr 22 09:53:39 IST 2017
Executed task on :: Mon Apr 22 09:53:44 IST 2017

2. Extend java.util.TimerTask

Using this way, we define out timer task by extending java.util.TimerTask and pass it to spring configuration for executing it repeatedly.

Lets see, how to do it:

<beans>

    <bean id="demoTimerTask" class="com.howtodoinjava.task.DemoTimerTask2"></bean>

    <bean id="scheduledTimerTask" class="org.springframework.scheduling.timer.ScheduledTimerTask">
	    <!-- run every 3 secs -->
	    <property name="period" value="3000"></property>
	    <property name="timerTask" ref="demoTimerTask"></property>
	</bean>

	<bean class="org.springframework.scheduling.timer.TimerFactoryBean">
	    <property name="scheduledTimerTasks">
	        <list>
	            <ref local="scheduledTimerTask"></ref>
	        </list>
	    </property>
	</bean>

</beans>

Above task will get executed in every 3 seconds. Lets extend out timer task from TimerTask provided by java.

package com.howtodoinjava.task;

import java.util.Date;
import java.util.TimerTask;

public class DemoTimerTask2 extends TimerTask 
{
	public void run() 
	{
		System.out.println("DemoTimerTask2 running at: "
				+ new Date(this.scheduledExecutionTime()));
	}
}

Lets test the configuration:

package com.howtodoinjava.timer;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestDemoTimerTask2 
{
	public static void main(String[] args) 
	{
		new ClassPathXmlApplicationContext("application-config2.xml");
	}
}

DemoTimerTask2 running at: Mon Apr 22 10:01:33 IST 2013
DemoTimerTask2 running at: Mon Apr 22 10:01:36 IST 2013
DemoTimerTask2 running at: Mon Apr 22 10:01:39 IST 2013

Happy Learning !!