是否可以从Servlet重定向到同一个JSP页面？

Question

A JSP page named Test.jsp is mapped to the following Servlet.

@WebServlet(name = "TestServlet", urlPatterns = {"/TestServlet"})
public final class TestServlet extends HttpServlet
{
    protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        //request.getRequestDispatcher("/WEB-INF/admin_side/Test.jsp").forward(request, response);
       response.sendRedirect("TestServlet");
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        processRequest(request, response);
    }

    @Override
    public String getServletInfo() {
        return "Short description";
    }
}

This Servlet is mapped to a JSP page Test.jsp . The doGet() method is invoked, when a URL like http://localhost:8080/Assignment/TestServlet is entered in the address bar.

The request can be forwarded to the given URL as commented out. Is it possible to redirect to the same JSP page, Test.jsp ?

If an attempt is made to do so, Google Chrome complains,

This webpage has a redirect loop

It can however, redirect to other pages under WEB-INF/admin_side .

Answer 1

The POST-REDIRECT-GET pattern works like so.

A client sends a POST request, your server handles it and responds with a redirect, ie. a response with a 302 status code and Location header to the appropriate URI. The client makes a GET request to that URI.

Currently, your server is redirecting on both GET and POSTS requests. What's worse is that your GET is redirecting to the same URI that it is handling, creating the redirect loop you are seeing.

Change your Servlet implementation so that the POST sends a redirect, but the GET actually serves up a normal 200 response with HTML, AJAX, etc.