How to schedule a task in Tomcat

Question

I have a web application deployed in Tomcat. I have a set of code in it, that checks database for certain data and then sends a mail to users depending on that data. Can somebody suggest how to schedule this in Tomcat.

Answer 1

Actually, the best way to schedule task in Tomcat is to use ScheduledExecutorService. TimeTask should not be used in J2E applications, this is not a good practice.

Example with the right way :

create a package different that you controller one (servlet package), and create a new java class on this new package as example :

// your package import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import javax.servlet.annotation.WebListener; @WebListener public class BackgroundJobManager implements ServletContextListener {  private ScheduledExecutorService scheduler;  @Override public void contextInitialized(ServletContextEvent event) {     scheduler = Executors.newSingleThreadScheduledExecutor();    // scheduler.scheduleAtFixedRate(new DailyJob(), 0, 1, TimeUnit.DAYS);     scheduler.scheduleAtFixedRate(new HourlyJob(), 0, 1, TimeUnit.HOURS);    //scheduler.scheduleAtFixedRate(new MinJob(), 0, 1, TimeUnit.MINUTES);    // scheduler.scheduleAtFixedRate(new SecJob(), 0, 15, TimeUnit.SECONDS); }  @Override public void contextDestroyed(ServletContextEvent event) {     scheduler.shutdownNow();  }  } 

After that you can create other java class (one per schedule) as follow :

public class HourlyJob implements Runnable {  @Override public void run() {     // Do your hourly job here.     System.out.println("Job trigged by scheduler");   } } 

Enjoy :)