RequestDispatcher help

[Maximilian]

So im trying to uncouple my rather tightly coupled webpage by using a FrontController servlet that will route all requests to the other servlets, it comtains code like:

if (currentRequestString.equals(GlobalValues.getDesktopLoginPage()))
        {
            System.out.println("Desktop login path");
            rd = request.getRequestDispatcher("/"+"LoginPageServlet");
            rd.forward(request, response);
        }
        else if (currentRequestString.equals(GlobalValues.getMobileLoginPage()))
        {
            System.out.println("Mobile login path");
            rd = request.getRequestDispatcher("/"+"LoginPageServlet");
            rd.forward(request, response);
        }

And so on... They both go to the same servlet right now, thats okay though. Here is the LoginPageServlet code that the FrontController sends these particular requests to:

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {   
        System.out.println("LoginPageServlet executing");
        HttpSession session = request.getSession(false);
        if(session == null) //path for invalid session
        {
            response.sendRedirect("desktopLogin.html");
        }
        else if(session.getAttribute("username") == null) //path for invalid username
        {
            //no username in session
            //user probably hasn't logged in properly
            response.setContentType("text/html");
            response.sendRedirect("desktopLogin.html");
        }
        else //path for valid session
        {
            response.sendRedirect("alreadyLoggedIn.html");
            
        }
    }

Unfortunately this redirects to the URL: "http://localhost:8080/fitness_tracker_servlet_maven/FrontController/desktopLogin.html"

When what I want it to do is redirect to:
"http://localhost:8080/fitness_tracker_servlet_maven/desktopLogin.html"

I assume this is because I am using RequestDispatcher and I theres something im missing about how it all works. I can fix it by doing this:

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {   
        System.out.println("LoginPageServlet executing");
        HttpSession session = request.getSession(false);
        if(session == null) //path for invalid session
        {
            response.sendRedirect[B]("/fitness_tracker_servlet_maven/desktopLogin.html")[/B];
        }
        else if(session.getAttribute("username") == null) //path for invalid username
        {
            //no username in session
            //user probably hasn't logged in properly
            response.setContentType("text/html");
            response.sendRedirect[B]("/fitness_tracker_servlet_maven/desktopLogin.html")[/B];
        }
        else //path for valid session
        {
            response.sendRedirect("alreadyLoggedIn.html");
            
        }
    }

But it would still be good to know why that happens with "FrontController" being part of the URL response.

 

[Maximilian]

Hmm I found ServletContext and I guess I can do this with LoginPageServlet:

public class LoginPageServlet extends HttpServlet
{

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {   
        System.out.println("LoginPageServlet executing");
        HttpSession session = request.getSession(false);
        if(session == null) //path for invalid session
        {
            ServletContext sc = this.getServletContext();
            response.sendRedirect(sc.getContextPath() +"/"+ GlobalValues.getDesktopLoginPage());
        }
        else if(session.getAttribute("username") == null) //path for invalid username
        {
            //no username in session
            //user probably hasn't logged in properly
            ServletContext sc = this.getServletContext();
            response.sendRedirect(sc.getContextPath() +"/"+ GlobalValues.getDesktopLoginPage());
        }
        else //path for valid session
        {
            response.sendRedirect("alreadyLoggedIn.html");
            
        }
    }

Weird thing though... It needs that "/" to be directly there in the servlet to work. GlobalValues.getDesktopLoginPage() returns the string "desktopLogin.html"

It will not work if I put the slash into the GlobalValues class and GlobalValues.getDesktopLoginPage() returns "/desktopLogin.html" the slash just gets ignored 😕

 

[purbeast0]

from the docs...

void sendRedirect(String location)
throws IOException

Sends a temporary redirect response to the client using the specified redirect location URL. This method can accept relative URLs; the servlet container must convert the relative URL to an absolute URL before sending the response to the client. If the location is relative without a leading '/' the container interprets it as relative to the current request URI. If the location is relative with a leading '/' the container interprets it as relative to the servlet container root.