Java EE Enterprise Application: perform some actio

Question

This question already has an answer here:

• Using special auto start servlet to initialize on startup and share application data 1 answer

I would like to perform some action as soon as my application (Enterprise Application with Business Logic, EJB, and a Client, Web) is deployed. For example I would like to make some entity in a persistent state, or otherwise create a file. How can I do that?

Thanks.

Answer 1

The "default" way is to have a servlet with an init() method. Then in the servlet-descriptor you mark this servlet as load-on-startup 1:

Example:

<servlet-name>Seam Resource Servlet</servlet-name>
   <servlet-class>org.jboss.seam.servlet.SeamResourceServlet</servlet-class>
   <load-on-startup>1</load-on-startup>
</servlet>

As soon as the servlet is deployed (which happens after the EJBs are deployed), that init() method is called and you can execute the task you want.

Answer 2

With present web application in your ear, the easiest and simplest would be to use ServletContextListener, otherwise in EJB 3.1 you could use automatic timers or startup singleton session beans.

Answer 3

Configure SerlvetContextListener and override contextInitilized()

in your web application description , web.xml

<web-app ...>
    <listener>
        <listener-class>com.someCompany.AppNameServletContextListener</listener-class>
    </listener>
</web-app

---

package com.someCompany;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class AppNameServletContextListener implements ServletContextListener{

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        System.out.println("ServletContextListener destroyed");
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        System.out.println("ServletContextListener started");   
                // do the things here 
    }
}