Java Tutorial/Servlet/RequestDispatcher

Servlet Controller Dispatcher

   <source lang="java">

import java.io.*; import javax.servlet.*; import javax.servlet.http.*; import java.util.*; public class MyServlet extends HttpServlet {

   public void doGet(HttpServletRequest request, 
       HttpServletResponse response) 
        throws ServletException, java.io.IOException {
       RequestDispatcher dispatcher = null;
       String param = request.getParameter("go");
            if (param == null)
                throw new 
                    ServletException("Missing parameter in Controller.");
            else if (param.equals("weather"))
                dispatcher = getServletContext().
                    getNamedDispatcher("Weather");
            else if (param.equals("maps"))
                dispatcher = getServletContext().
                    getNamedDispatcher("Maps");
           else
               throw new ServletException(
                   "Improper parameter passed to Controller.");
        /*check for a null dispatcher, then 
           dispatch the request to the correct URL*/
       if (dispatcher != null)
           dispatcher.forward(request,response);
       else
           throw new ServletException(
             "Controller received a null dispatcher.");
   }

}</source>

Servlet Forwarding Dispatch

   <source lang="java">

import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class MyServlet extends HttpServlet {

 public void doGet (HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
 {
    ServletContext context = getServletContext();
    RequestDispatcher dispatcher = context.getRequestDispatcher("/myServlet");
    dispatcher.forward(req,res);
 }

}</source>