Job Scheduling Using Quartz

Quartz is suitable when an application must run tasks at a specific time or execute recurring maintenance operations automatically.

Create the Environment

Wait until the environment provisioning process is complete.

Create the Application

Create a Java web application. The source example uses a Maven-based project with Quartz libraries included in the project dependencies.

Add Quartz Dependencies

Add the following dependencies to the project’s pom.xml file:

<!-- Quartz API -->
<dependency>
    <groupId>opensymphony</groupId>
    <artifactId>quartz</artifactId>
    <version>1.6.3</version>
</dependency>

<dependency>
    <groupId>commons-collections</groupId>
    <artifactId>commons-collections</artifactId>
    <version>3.2.1</version>
</dependency>

<dependency>
    <groupId>org.apache.directory.studio</groupId>
    <artifactId>org.apache.commons.logging</artifactId>
    <version>1.1.1</version>
</dependency>

Build the project after adding the required dependencies.

Create the Scheduled Job

Create a Java class that implements the Quartz Job interface. The following example writes the server time to the application log:

package com;

import java.util.Date;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;

public class HelloJob implements Job {

    public void execute(JobExecutionContext context)
            throws JobExecutionException {

        System.out.println("Server Time: " + new Date());
    }
}

Create the Quartz Servlet

Create a servlet that defines the Quartz job and its trigger. In this example, the scheduler runs the HelloJob class every minute.

package com;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.ParseException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.quartz.CronTrigger;
import org.quartz.JobDetail;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.impl.StdSchedulerFactory;

public class QuartzServlet extends HttpServlet {

    protected void processRequest(
            HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        try {
            JobDetail job = new JobDetail();
            job.setName("dummyJobName");
            job.setJobClass(HelloJob.class);

            CronTrigger trigger = new CronTrigger();
            trigger.setName("TriggerName");
            trigger.setCronExpression("0 */1 * * * ?");

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

            scheduler.start();
            scheduler.scheduleJob(job, trigger);

        } catch (SchedulerException ex) {
            Logger.getLogger(QuartzServlet.class.getName())
                  .log(Level.SEVERE, null, ex);

        } catch (ParseException ex) {
            Logger.getLogger(QuartzServlet.class.getName())
                  .log(Level.SEVERE, null, ex);

        } finally {
            out.close();
        }
    }

    protected void doGet(
            HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {

        processRequest(request, response);
    }

    protected void doPost(
            HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {

        processRequest(request, response);
    }

    public String getServletInfo() {
        return "Short description";
    }
}

Build the completed application into a WAR archive.

Deploy the Application

Verify the Scheduler

Open the application in a browser using the mapped servlet context. The example uses:

http://{env_name}.{hoster_domain}/quartz

Open the Tomcat log to review the scheduler output.

What’s next?