Solved

Servlet controller and RequestDispatcher

Posted on 2006-06-28
5
367 Views
Last Modified: 2013-11-24
Hi Experts,

I am trying to control all users' requests by one servlet and then it passes it to the next servlet based on the request. However, I only get blank page instead of welcome page if I request from  login page.

This is what I did.
+++++++++++++++++++++

login.html

...
<FORM ACTION="RegistrationController" METHOD="POST">
...
...
++++++++++++++++

public class RegistrationController extends HttpServlet {
   
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, java.io.IOException {
               
                RequestDispatcher rd = request.getRequestDispatcher("/LoginServlet");
                rd.include( request, response ) ;  
...
...
++++++++++++
public class LoginServlet extends HttpServlet {
   
   
     protected void doGet(HttpServletRequest request,
             HttpServletResponse response)
             throws ServletException, java.io.IOException {
         response.sendRedirect("/AS4/welcome.html");
....
...
++++++++++++
      <servlet>
            <servlet-name>RegistrationController</servlet-name>
            <servlet-class>RegistrationController</servlet-class>
      </servlet>
      <servlet>
            <servlet-name>LoginServlet</servlet-name>
            <servlet-class>LoginServlet</servlet-class>
      </servlet>
      
      <servlet-mapping>
           <servlet-name>RegistrationController</servlet-name>
           <url-pattern>/RegistrationController</url-pattern>
        </servlet-mapping>

        <servlet-mapping>
           <servlet-name>LoginServlet</servlet-name>
           <url-pattern>/*</url-pattern>
        </servlet-mapping>
+++++++++++

thanks in advance
0
Comment
Question by:dkim18
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5 Comments
 
LVL 10

Expert Comment

by:mukundha_expert
ID: 17003331
if you are getting the correct URL on the browser then try including or forwarding to the welcome.html  instead of redirecting it in LoginServlet

0
 

Author Comment

by:dkim18
ID: 17003441
I don't think I am getting correct url. This is url that I got:

http://localhost:8080/AS4/RegistrationController

and acutally, there is error message on the screen that says:

The requested resource (/AS4/LoginServlet) is not available

0
 
LVL 10

Accepted Solution

by:
mukundha_expert earned 300 total points
ID: 17003568
try,

public class RegistrationController extends HttpServlet {
   
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, java.io.IOException {
               
                RequestDispatcher rd = request.getRequestDispatcher("/LoginServlet");
               ////////************ rd.include( request, response ) ;  

              rd.forward(request,response) ;

...
...



>>>>>>>>>>>> use system.out.println() in both the servlets, you can easily find where it is going wrong. rd.include() did not work. coz include includes the output of the other servlet into this. forward() gives the control to the new servlet.

check,

http://www.brics.dk/~amoeller/WWW/servlets/dispatch.html


0
 
LVL 10

Expert Comment

by:mukundha_expert
ID: 17003581
also try changing this,

<servlet-mapping>
           <servlet-name>LoginServlet</servlet-name>
           <url-pattern>/LoginServlet</url-pattern>
        </servlet-mapping>
0
 

Author Comment

by:dkim18
ID: 17003643
Yes, it worked. I didn't even have to change servlet mapping. Thanks!
0

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