Starting a worker thread in a Servlet Engine

Today's example shows how to create a background thread when your servlet context starts up, and how to end the thread's activities gracefully when the servlet context is destroyed. Take this example and add it as a "listener" in your web application, then using the Tomcat (or equivalent) manager start and stop the context and watch the stdout messages.

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class Deamon implements ServletContextListener, Runnable {

   private Thread t;

   public void contextDestroyed(ServletContextEvent arg0) {
      t.interrupt();}

   public void contextInitialized(ServletContextEvent context) {
      t = new Thread(this);
      t.start();
      System.out.println("deamon started");}

   public void run() {
      try {
         while (true) {
            System.out.println("deamon working...");
            Thread.sleep(1000);
         }
      } catch (InterruptedException e) {
         System.out.println("deamon stopped");}
   }
}