Is there a way to run a method/class only on Tomcat/Wildfly/Glassfish startup?

Question

I need to remove temp files on Tomcat startup, the pass to a folder which contains temp files is in applicationContext.xml.

Is there a way to run a method/class only on Tomcat startup?

Carlyncarlynn

UPDATE: I had a temporary malfunction - you should use a ContextListener, not a SessionListener. – Braca

Answer 1

You could write a ServletContextListener which calls your method from the contextInitialized() method. You attach the listener to your webapp in web.xml, e.g.

<listener>
   <listener-class>my.Listener</listener-class>
</listener>

and

package my;

public class Listener implements javax.servlet.ServletContextListener {

   public void contextInitialized(ServletContext context) {
      MyOtherClass.callMe();
   }
}

Strictly speaking, this is only run once on webapp startup, rather than Tomcat startup, but that may amount to the same thing.

Halogen

This is also portable across Java servlet containers. The best way in my opinion. Other options are listed here- blog.eisele.net/2010/12/… – Dario

@Halogen but during the tomcat server in eclipse starts contextInitialized() function is calling but MyClass.INSTANCE is not calling.MyClass is a enum class and it creating INSTANCE once.Tomcat fails to start. the code is public void contextInitialized(ServletContextEvent contextEvent) { MongoDBClass.INSTANCE.getSomeDB().getCollection("UserDB"); context = contextEvent.getServletContext(); MongoDBClass.INSTANCE.getSomeDB().getCollection("UserDB"); } – Oneness

Answer 2

You can also use (starting Servlet v3) an annotated aproach (no need to add anything to web.xml):

   @WebListener
    public class InitializeListner implements ServletContextListener {

        @Override
        public final void contextInitialized(final ServletContextEvent sce) {

        }

        @Override
        public final void contextDestroyed(final ServletContextEvent sce) {

        }
    }

Heathen

Can i add http server starting code within contextInitialized. Because after adding this am messed up with exception and errors – Kowalewski

Answer 3

I'm sure there must be a better way to do it as part of the container's lifecycle (edit: Hank has the answer - I was wondering why he was suggesting a SessonListener before I answered), but you could create a Servlet which has no other purpose than to perform one-time actions when the server is started:

<servlet>
  <description>Does stuff on container startup</description>
  <display-name>StartupServlet</display-name>
  <servlet-name>StartupServlet</servlet-name>
  <servlet-class>com.foo.bar.servlets.StartupServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
</servlet> 

Euripus

Before Servlet 2.4 (or was it 2.3?), that's what people did. But with the addition of context listeners, this is no longer necessary. – Halogen

That's good tp know - a legacy application we're "refactoring" (it's not a rewrite from the ground up with a better framework and requirements changing all over the place, honest!) at the moment to run on a 2.4 container is still using this technique. – Euripus