Untitled

import javax.servlet.*;
    import javax.servlet.http.*;
    import java.io.*;
    import java.util.*;

    public class HiddenParamServlet extends HttpServlet {


        private final String[] PARAMS = { "name", "surname", "e-mail" };
        private Map<String, String> hiddenParameters;

        @Override
        public void init() {
            hiddenParameters = new HashMap<String, String>();
        }
        @Override
        public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

            response.setContentType("text/html");
            PrintWriter out = response.getWriter();

    // control the last parameter added by the client
            List<String> clientParameters =        Collections.list(request.getParameterNames());

    // checks if the client already sent all the parameters
            if(clientParameters.size() == 3) {
            // start the html document
                out.println("<html><head><title>Session finished</title></head>");
                out.println("<body><h1>Session succesfully completed</h1></body>");
                out.println("</html>");
            // end the html
                out.close();

                hiddenParameters.clear();
           }

           else {

              String lastParam = clientParameters.get(clientParameters.size() -1);
        //memorizing the last param sent by the client
              String value = request.getParameter(lastParam);
        hiddenParameters.put(lastParam, value);

        // starts the HTML document
              out.println("<html>");
              out.println("<head><title>Tracking session with hidden parameters</title></head>");

              out.println("<body>");
              out.println("<form method="get" action="/DirectoryDiSaluto/HiddenParamServlet">");
        out.println("<p>");

        //write the next parameter to ask to the client
              out.println("<label>Insert "+PARAMS[clientParameters.size()]+":");

        // write the hidden parameters of the server
              for(String key : hiddenParameters.keySet()) {
                   out.println("<input type="hidden" name=""
            +key+"" value=""+hiddenParameters.get(key)+"" />");
              }
              out.println("<input type="text" name=""+PARAMS[clientParameters.size()]+"" />");
              out.println("<input type="submit" value="Submit" />");
              out.println("</label>");
              out.println("</p>");
              out.println("</form>");
              out.println("</body>");
              out.println("</html>");
        // end the html

              out.close();
            }
         }

    }

<html>
      <head>
          <title>Tracking session with hidden parameters</title>
      </head>

      <body>

        <form method="get" action="/DirectoryDiSaluto/HiddenParamServlet">
            <p>
            <label>Insert name:
                <input type="text" name="name"/>
                <input type="submit" value="Submit" />
            </label>
           </p>
        </form>
      </body>
   </html>