Problem in Servlet Request Attribute Listener

[Micheal John]

Hi all,

I am trying a example on ServletRequestAttributeListener. It's giving error:

package com.example.web;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class RequestAttrListener extends HttpServlet implements ServletRequestAttributeListener{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
request.setAttribute("a", "Hello");
request.setAttribute("a", "Hello World");
request.setAttribute("b", "Hi");
request.removeAttribute("a");
}
public void attributeAdded(ServletRequestAttributeEvent event){
System.out.println("A :"+ event.getName() + "->" +event.getValue());
}
public void attributeReplaced(ServletRequestAttributeEvent event){
System.out.println("M :"+ event.getName() + "->" +event.getValue());
}
public void attributeRemoved(ServletRequestAttributeEvent event){
System.out.println("R :"+ event.getName() + "->" +event.getValue());
}
}

com\example\web\RequestAttrListener.java:7: cannot find symbol
symbol: class ServletRequestAttributeListener
public class RequestAttrListener extends HttpServlet implements ServletRequestAt
tributeListener{
^
com\example\web\RequestAttrListener.java:20: cannot find symbol
symbol : class ServletRequestAttributeEvent
location: class com.example.web.RequestAttrListener
public void attributeAdded(ServletRequestAttributeEvent event){
^
com\example\web\RequestAttrListener.java:24: cannot find symbol
symbol : class ServletRequestAttributeEvent
location: class com.example.web.RequestAttrListener
public void attributeReplaced(ServletRequestAttributeEvent event){
^
com\example\web\RequestAttrListener.java:28: cannot find symbol
symbol : class ServletRequestAttributeEvent
location: class com.example.web.RequestAttrListener
public void attributeRemoved(ServletRequestAttributeEvent event){
^
4 errors

Whether for this also, we havr to register in web.xml like below

<listener>
<listener-class>
com.example.model.RequestAttrListener
</listener-class>
</listener>

[Sreeraj G Harilal]

Nothing wrong with your code. It works fine.
Please check your classpath or other tomcat settings.

[VijayKumar Sivagnanam]

Hi Micheal,

You have to register the ServletRequestAttributeListener in the web.xml. Try it and let me know.

[Cameron Wallace McKenzie]

You definintely need to add an entry into your web.xml file. Make sure it is there. Although, I would have thought that if it wasn't there, it would just be ignored, as opposed to causing a runtime error?

I have a bunch of tutorials on my website about J2EE and web development. One deals with Listeners, although it is a session listener, as opposed to a request listener. Still, it's the same idea. Plus, the web.xml code is on the page. It might be helpful:

Tutorial on Configuring Listeners in a Servlet/JSP Based Application - With Code!

I hope that helps.

-Cameron McKenzie

[Micheal John]

I have registerd in the web.xml..

I have the following classpath:
D:\jdk1.5.0_01\lib\servlet.jar;D:\jdk1.5.0_01\lib\xerces-2.3.0;D:\jdk1.5.0_01\lib\xml-apis;.;

I have the below import statemnt:
import javax.servlet.*; //(which will cover all)
import javax.servlet.http.*;//(which will cover all)
import java.io.*;

Other servlets and JSP are compiling & running fine..even I tried the ServletContextListener example from HFSJ and it's wirks fine..

I think it shouldn't be a classpath problem..

And also,Whether for all Listener interfaces, where (in which class) the implementation is implemented does matter? What will be the pros and cons or any guidelines for it?pls explain

Any glue..?
[ December 30, 2006: Message edited by: Micheal John ]

[Micheal John]

Hi,
I couldn't figure out the problem..any help...?

[VijayKumar Sivagnanam]

Hi Michael,

You are having the listener in your servlet itself. Try creating the listener separately and give a try.