Problem with Servlets

From:

"kmr.kishore@gmail.com" <kmr.kishore@gmail.com>

Newsgroups:

comp.lang.java.help

Date:

Fri, 09 Nov 2007 06:10:59 -0800

Message-ID:

<1194617459.713672.36450@e34g2000pro.googlegroups.com>

the servlet program is :

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class LoginServlet extends HttpServlet
{
    public void doPost(HttpServletRequest req,HttpServletResponse res)
                  throws ServletException,IOException {

         res.setContentType("text/html");
         PrintWriter out = res.getWriter();
         String id = req.getParameter("id");
         String password = req.getParameter("pwd");
         out.println("<HTML><BODY>");
         if("jsmith".equalsIgnoreCase(id) &&
"spring12".equalsIgnoreCase(password))
         {
             out.println("Hello," + id + "Welcome to My World");
         }
         else
        {
            out.println("Id/Password combonation is not valid");
        }
        out.println("<BODY></HTML>");
                  }
}

the html program is:

<html>
<head>
<title>Servlet Example</title>
</head>

<body>
<P>
<form action = "servlet/LoginServlet" method=Post>
Enter Login ID: <input type=text name="id">
<P>
Enter Password:<input type=Password name="pwd">
<P>
<input type="Submit" value="Login">
<input type="Reset">
</form>
</body>
</html>

the class path and path variables are:

path : d:\java\jdk1.5.0_06\bin;
classpath: c:\Program Files\Java\jre1.5.0_06\lib\rt.jar;d:\Apache
Software Foundation\....\..\servlet-api.jar;
My Problem is :
I can start the server by going to localhost:8080 port and my
application is displayed there.
and when i click the folder in the table shown all registered
application with tomcat, the login form is displayed but when i click
the submit button there is an error message is coming.

I found that in the example prokjects there is a web.xml file for each
application giving the description about servlets.is it necessary?if
so, pls tell me how to write that xml file for my servlet?
Thank,Regards Kishore