[FIXED] How to Map Servlet Actions to JSP Path with Annotations?

Issue

I have a simple Maven servlet/jsp application that I deploy to a local Tomcat 9 (via Eclipse). JSP pages are stored under root folder (src\main\webapp\*.jsp) which when Maven installs a WAR, they go under the root folder (MyAppContext\*.jsp along side MyAppContext\META-INF\ and MyAppContext\WEB-INF\).

The servlets' URL patterns are annotated for each servlet, e.g. /doactionone, /doactiontwo, etc. Most servlets perform the dispatching to various JSP pages, but I do have a direct anchor link on one.

I wanted to move these JSP pages into their own respective directory, so I moved them to src\main\webapp\jsp\*.jsp folder, and when the Maven install is run, they get placed under MyAppContext\jsp\.

The only entry I have in web.xml is a welcome file that after relocating the JSP files, it points to jsp\doactionone.jsp which loads that corresponding JSP page. This page contains a simple form:

<form action="doactionone" method="post">
    ...
    <a href="jsp/doactiontwo.jsp">
    <input type="submit" />...
</form>

The submission on this page actually calls the right servlet (the one defined with doactionone URL pattern). I also have a link that takes the user to the second page (doactiontwo.jsp).

However, when I navigate to that second page via this link, which has another simple form (see below), and perform the submission (post), I see in browser's debugging that the URL request is http://localhost:8080/MyAppContext/jsp/doactiontwo which, for obvious reason, would return a 404 status (and get no hit to this servlet's doPost() (or doGet()) methods either).

<form action="doactiontwo" method="post">
    ...
    <input type="submit" />...
</form>

If I try to modify the second servlet's URL pattern to /jsp/doactiontwo, I can hit the servlet, but when doactiontwo actually dispatches/forwards the request after processing to the first servlet (doactionone) with:

RequestDispatcher rd = request.getRequestDispatcher("doactionone.jsp");
rd.forward(request, response);

when it gets loaded, when hover over the URL on the first page that initially was pointing to the second JSP page (<a href="jsp/doactiontwo.jsp">), now actually points to:

jsp/jsp/doactiontwo.jsp

The funny part is that the source code of doactionone.jsp still shows it as jsp/doactiontwo.jsp, but hovering over it shows http://localhost:8080/MyAppContext/jsp/jsp/doactiontwo, and when clicked, it obviously results in 404 status.

Can somebody explain why, first of all, the submission on the second JSP page requires the servlet to have a pattern of /jsp/doactiontwo to work rather than /doactiontwo? And is there a way around to avoid appending /jsp to the URL pattern?

And second, why when the second servlet processes the request and dispatches/forwards it to the first page, the URL now contains two jsp/'s?

Solution

You need to change your design to allow the controllers, a.k.a. Servlets, to drive your application. In this particular case, use the URL Pattern of second Servlet (doactiontwo) in place of you link:

@WebServlet(urlPatterns = { "doactiontwo" }
public class DoActionTwoServlet extends HttpServlet { /* ... */ }

<form action="doactionone" method="post">
    ...
    <a href="doactiontwo"> <!-- This should match your second servlet's URL pattern -->
    <input type="submit" />...
</form>

Now, since the default method when anchor link is invoked is GET, you need to overwrite DoActionTwoServlet's doGet() method, and forward those requests to an actual doactiontwo.jsp:

public void doGet(HttpServletRequest req, HttpServletResponse res)
  throws ServletException, IOException  {

     RequestDispatcher rd = request.getRequestDispatcher("jsp/doactiontwo.jsp");
     rd.forward(request, response);
}

Answered By - Malvon