Domino & REST: Listeners for Initialization & Destroying of a Servlet

If you need to know when your Servlet is initialized or destroyed, you can use a ServletContextListener in your application.

First, create the class AppServletContextListener and implement the javax.servlet.ServletContextListener interface. This provides two methods for capturing the events: contextInitialized and contextDestroyed:

package ch.hasselba.servlet;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class AppServletContextListener
               implements ServletContextListener{

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        System.out.println("ServletContextListener destroyed");
    }

    @Override
    public void contextInitialized(ServletContextEvent event) {
        System.out.println("ServletContextListener started");
    }
}

The ServletContextEvent allows you to access the ServletContext if required.

Now you have to register the listener in your web.xml:

<web-app>
     <listener>
         <listener-class>
             ch.hasselba.servlet.AppServletContextListener
         </listener-class>
    </listener>
</web-app>

As soon as you start or stop the HTTP task, the Listener is called, and you can execute some application specific code (i.e. shutdown threads, bring out the garbage, etc.)