How can I trigger servlet while Tomcat starting time

Question

we develops a project name as FirstApplication for sending,consuming messages from Activemq and deployed in Tomcat7.After deploying,we have to trigger http://localhost:8080/FirstApplication/PackageName/SecondConsumer link only 1 time.So far it's fine.

My doubt,later If we restart the server,again first time we have to trigger that servlet corresponding link.Instead of doing like this,I want to configure.

Note: what I want,servlet should be evaluate automatically whenever Tomcat server start.servlet placed under WebApps/FirstApplication/WEB-INF/src/classes/PackageName/SecondConsumer.java.

For this, I tried with the following code using servletContextListenerclass.

 public class SecondConsumer extends HttpServlet implements ServletContextListener{
 @Override
 protected void service(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
   //my business code
 }
 @Override
 public void contextDestroyed(ServletContextEvent arg0) {
// TODO Auto-generated method stub

 }

 @Override
 public void contextInitialized(ServletContextEvent arg0) {
// TODO Auto-generated method stub

 }
}

and added <Listener>in my web.xml(which is placed under WebApps/FirstApplication/WEB-INF/web.xml) file in the following way.

    <listener>
    <listener-class>PackageName.SecondConsumer</listener-class>
   </listener>

If you observe my code, I didn't implement any code under contextInitialized and contextDestroyed methods.Just i want to evaluate this servlet code while server starting time.

I tried in the above way,it's not working.

please can anyone suggest me.

Thanks.

score 4 · Accepted Answer · answered Sep 16 '13 at 19:12

4

You should do your initialization in a class which implements ServletContextListener, so you need something like this

@WebListener
public class AppServletContextListener implements ServletContextListener{

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

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
         //do your init steps here  
    }
}

This piece of code will execute whenever your server starts or stops. Note that WebListener annotation works only in Java EE 6, prior to that you would need to define <listener> element in a web.xml.

answered Sep 16 '13 at 19:12

Petr Mensik

26,874
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you mean Am I need to write one more java file.Basically I am not a `Java` developer so can you explain clearly.Am I need to define `Listener` element into my `WebApps/firstApplication/WEB-INF/web.xml`. – Hanumath Sep 16 '13 at 19:18
Yes, this will be a new class (file). No, you don't need to define `` element in web.xml, `@WebListener` annotation is enough (in case you use Java EE 6 - which you probably do). – Petr Mensik Sep 16 '13 at 19:22
I modified my question with what I tried based on your suggestion.it's not working.can you check it once whether is it right. – Hanumath Sep 16 '13 at 19:56
You really can't extend `HttpServlet` so remove that declaration from your listener and it should work then. Your listener is simply just not a servlet, it's just a listener which allows you to execute some code upon server startup or end. – Petr Mensik Sep 17 '13 at 06:48
Thanks you.. I got it it's working fine without servlet – Hanumath Sep 17 '13 at 12:29

score 1 · Answer 2 · answered Sep 16 '13 at 19:07

1

Tomcat while running create an instance of servlet, so if you want to invoke servlet please use context listner class which actually triggers while running tomcat itself.

Thanks

answered Sep 16 '13 at 19:07

geekIndiana

87
4
14

Basically I am not a `Java` developer. If you know any tutorials about this suggest me or can you explain clearly with my names(What I mention in my question). – Hanumath Sep 16 '13 at 19:12
This link will help you to understand the basic of contextlistner - [link](http://www.mkyong.com/servlet/what-is-listener-servletcontextlistener-example/) – geekIndiana Sep 16 '13 at 19:20

score 0 · Answer 3 · answered Sep 16 '13 at 19:12

0

I am not quite sure, what you want. If you simply want to execute code while starting up the tomcat, you con configure a ServletContextListener

answered Sep 16 '13 at 19:12

Christian Kuetbach

15,850
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How can I trigger servlet while Tomcat starting time

3 Answers3