What is Quartz scheduler and how to use it ?

Quartz is a powerful and advance scheduler framework used to schedule a job to run at a specified date and time.

1. Download Quartz

Site : http://www.quartz-scheduler.org

Dependencies : quartz 1.6.3, commons-collections 3.2.1, org.apache.commons.logging 1.1.1

2. Quartz Job

• Defines what you want to run ?

public class MyJob implements Job {

    public void execute(JobExecutionContext context) throws JobExecutionException { 

        System.out.println("Hello Quartz!");    

    } 

}

3. Quartz Trigger

• Defined when the Quartz will run your above Quartz’s job ?
• 2 types of Quartz triggers : Simple and Cron triggers

a. SimpleTrigger : allows to set start time, end time, repeat count, repeat interval

SimpleTrigger trigger = new SimpleTrigger();

trigger.setName("myTriggerName");

trigger.setStartTime(new Date(System.currentTimeMillis() + 1000));

trigger.setRepeatCount(SimpleTrigger.REPEAT_INDEFINITELY);

trigger.setRepeatInterval(30000);   // Run every 30 seconds

b. CronTrigger : allows Linux CRON expression to specify the dates and times for the job

CronTrigger trigger = new CronTrigger();

trigger.setName("myTriggerName");

trigger.setCronExpression("0/30 * * * * ?");  // Run every 30 seconds

4. Scheduler (linking Job with Trigger)

Scheduler class links both “Job” and “Trigger” together and execute it.

Scheduler scheduler = new StdSchedulerFactory().getScheduler();

scheduler.start();

scheduler.scheduleJob(job, trigger);