Question

I’m developing JSP/Servlets App,and I want to execute a service at a specific time , for example :

For each day at 10:00 AM , delete any
attachment from the “attachment” table
in the database where column X== NULL.

How can I do this in JSP/Servlets application ?
I use Glassfish as a server .

Answer 1

• EJB3 Timer service or
• Use Quartz scheduler library, or
• perform hacks like folliwng:

Implement ServletContextListener ; in the contextInitialized method :

ServletContext servletContext = servletContextEvent.getServletContext();
try{
 // create the timer and timer task objects
  Timer timer = new Timer();
  MyTimerTask task = new MyTimerTask(); //this class implements Callable.

 // get a calendar to initialize the start time
  Calendar calendar = Calendar.getInstance();
 Date startTime = calendar.getTime();

  // schedule the task to run hourly
 timer.scheduleAtFixedRate(task, startTime, 1000 * 60 * 60);

  // save our timer for later use
  servletContext.setAttribute ("timer", timer);
} catch (Exception e) {
 servletContext.log ("Problem initializing the task that was to run hourly: " + e.getMessage ());
}

Edit your web.xml to have reference to your listener implementation:

<listener>
   <listener-class>your.package.declaration.MyServletContextListener</listener-class>
</listener>