How do you detect the URL in a Java Servlet when forwarding to JSP?

Question

I have a servlet that looks something like this:

public class ExampleServlet extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  response.getWriter().println(request.getPathInfo());
 }
}

with a web.xml mapping like:

<servlet>
 <servlet-name>example</servlet-name>
 <servlet-class>com.example.ExampleServlet</servlet-class>
</servlet>
<servlet-mapping>
 <servlet-name>example</servlet-name>
 <url-pattern>/example/*</url-pattern>
</servlet-mapping>

and it gives me exactly what I expect... If I go to http://localhost:8080/example/foo it prints "/foo". However, if I change the servlet to forward to a JSP file:

public class ExampleServlet extends HttpServlet {
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // do something here to check the value of request.getPathInfo()
  request.getRequestDispatcher("whatever.jsp").forward(request, response);
 }
}

then when I check the value of getPathInfo() it now reports "whatever.jsp" instead of "foo".

1. Why has this changed before it's been forwarded to the JSP?
2. How can I detect what URL the user's looking for?

EDIT: Just in case it matters this is on Google App Engine. Don't think it should though.

Answer 1

The URL the user (browser) requested can be accessed from the request by:

request.getRequestURL()

Alternatively the request has a whole bunch of accessors to get the various pieces of the URL as well as those on ServletRequest.

To redirect to a different URL change the response rather than the request:

response.sendRedirect(theURLToRedirectTo)

Answer 2

Suffering same issue.. calling getRequestURL from request forwarded to JSP. I suspect appengine is relevant as I am using that too (and don't remember coming across this prob in any other container)

Answer 3

The question is vague and ambiguous (is the servlet calling itself on every forward again?), but it much sounds like that you need request.getAttribute("javax.servlet.forward.request_uri").