Job scheduling with Quartz

 Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs.

Job Scheduling

Jobs are scheduled to run when a given Trigger occurs. Triggers can be created with nearly any combination of the following directives:

• at a certain time of day (to the millisecond)
• on certain days of the week
• on certain days of the month
• on certain days of the year
• not on certain days listed within a registered Calendar (such as business holidays)
• repeated a specific number of times
• repeated until a specific time/date
• repeated indefinitely
• repeated with a delay interval

Job Execution

• Jobs can be any Java class that implements the simple Job interface, leaving infinite possibilities for the work your Jobs can perform.
• Job class instances can be instantiated by Quartz, or by your application's framework.
• When a Trigger occurs, the scheduler notifies zero or more Java objects implementing the JobListener and TriggerListener interfaces.
• As Jobs are completed, they return a JobCompletionCode which informs the scheduler of success or failure.

First Quartz Program :

This example is designed to demonstrate how to get up and running with Quartz. This example will fire off a simple job that says "Hello Job".

The program will perform the following actions:

• Start up the Quartz Scheduler
• Schedule a job to run every 5 seconds
• Wait for 90 seconds to give Quartz a chance to run the job
• Shut down the Scheduler

HelloJob : 

HelloJob is a simple job that implements the Job interface and logs time exactly when the job is run.

public class HelloJob implements Job
{
    public void execute(JobExecutionContext context) throws JobExecutionException 
    {
        System.out.println("Hello Job! - "+ new Date());
    }
}

This QuartzSchedulerExample will create scheduler

public class QuartzSchedulerExample
{
    public static void main( String[] args ) throws Exception
    {
            
        JobDetail job = JobBuilder.newJob(HelloJob.class)
        .withIdentity("job1", "group1").build();
 
        Trigger trigger = TriggerBuilder
        .newTrigger()
        .withIdentity("trigger1", "group1")
        .withSchedule(CronScheduleBuilder.cronSchedule("0/5 * * * * ?"))
        .build();
 
        //schedule it
        Scheduler scheduler = new StdSchedulerFactory().getScheduler();
        scheduler.start();
        Thread.sleep(90L * 1000L);   
        scheduler.scheduleJob(job, trigger);
 
    }
}