Re: Maintaining form elements when using a servlet to redirect?

From:

Lew <lew@nowhere.com>

Newsgroups:

comp.lang.java.programmer

Date:

Fri, 01 Dec 2006 18:14:34 -0500

Message-ID:

<ZM6dnZ3QAL_HKu3YnZ2dnUVZ_qOdnZ2d@comcast.com>

Jim Bancroft wrote:

We're trying to use MVC in our J2EE application. We have a servlet that
acts as the controller. All our pages post to this servlet, which is
supposed to read one of the input values and forward to the appropriate
page. My question: is it possible for the servlet to "forward" all of the
form inputs to the page too?

Our code looks something like this:

            String action = request.getParameter("action");
            String aURL = locateTheAppropriateURL(action);
            RequestDispatcher requestDispatcher =
request.getRequestDispatcher(aURL);
            requestDispatcher.forward(request, response);

I don't see any mechanism for automatically passing along any other
form/request variables to the new page. Is there a good way of doing this?
Thanks!

richardsosborn@gmail.com wrote:

there are a couple options. my suggestion for you?
place everything in "session".

           HttpSession session = request.getSession();
           session.setAttribute(request.getParam("param1");
           session.setAttribute(request.getParam("param2");
           session.setAttribute(request.getParam("param3");
           session.setAttribute(request.getParam("param4");

By definition, request "variables", by which I assume you mean "parameters",
will come with the "request" parameter of the forward() method. So will any
attributes set via request.setAttribute(). No further action or "mechanism"
necessary.

In the target resource you simply dereference with request.getParameter(),
request.getAttribute() or the equivalent JSP constructs.

You should *not* place variables into the session unless their usage requires
session lifetime. It is silly to put them in the session just to pass them
redundantly with the request.

- Lew