Question

I want to have some code executed whenever my web-app deploys.

The same should happen if I re-start tomcat.

And this should be done only once in the life-cycle of the entire web-application.

Is there something which I can set in web.xml, something like a startup entry, which will be executed everytime I deploy my web-application or restart tomcat ?

Please help.

Answer 1

You need to implement ServletContextListner interface.

ServletContextListner is inside javax.servlet package.

Here is a brief code on how to do it.

public class MyServletContextListener implements ServletContextListener {

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
    //Notification that the servlet context is about to be shut down.   
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
    // do all the tasks that you need to perform just after the server starts

    //Notification that the web application initialization process is starting
    }

}

And configure it in your deployment descriptor web.xml

<listener>
    <listener-class>
        mypackage.MyServletContextListener
    </listener-class>
</listener>