[FIXED] Null value From request.getParameter

Issue

Login Controller:

package test;

import java.io.IOException;
import java.util.ArrayList;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.webappmvc.mvc.controller.Controller;

public class Login implements Controller{

    public void doProcess(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();

        System.out.println("UserName Parameter Value: " + request.getParameter("username"));

        if(request.getParameter("login") != null && request.getParameter("userName") != null && request.getParameter("password") != null){
            if(!request.getParameter("userName").equals("") && !request.getParameter("password").equals("") && request.getParameter("login").equals("Login")){
                ArrayList<String> data = (ArrayList<String>) request.getAttribute("model");
                for(int i=0; i<data.size(); i+=2){
                    System.out.println("Username from DB: " + data.get(i) + "\nPassword: " + data.get(i+1));
//                  if(request.getParameter("username").toString().equals(data.get(i))){
//                      if(request.getParameter("password").toString().equals(data.get(i+1).toString())){
//                          session.setAttribute("loggedUser", data.get(i).toString());
//                          response.sendRedirect("home");
//                          return;
//                      }
//                      request.setAttribute("errorMsg", "Invalid Login");
//                  }
                }
            }
        }
        System.out.println("Result view is: " + request.getAttribute("view"));
        request.getRequestDispatcher(request.getAttribute("view").toString()).forward(request, response);
    }

    public String addMapping() {

        return "/login";
    }

}

Here, Every request going through WebappController class defined in com.webappmvc.mvc.controller.Controller, com.webappmvc.mvc.controller.Controller#doGet method select controller, model, view on runtime, then forward it to com.webappmvc.mvc.controller.ResponseController#doGet Then, In response Controller, some code like this which forward request, response client project Controller#doProcess method.

Controller controller = (Controller) request.getAttribute("controller");
controller.doProcess(request, response);

With these, when i tried to acces /login, LoginController getting called, But getParameter() returning null each and every time. I also tried to acces this URL

Requested URL: http://localhost:8080/FreameworkTest/controller/login?userName=test&password=test&login=Login

I'm Getting Output in console like these.

Console Output:

All request passing through WebApp Controller //From WebAppController
 ----- From Response Controller //From WebAppResponseController

UserName Parameter Value: null  //From LoginController
Username from DB: jitu
Password: 12345
Result view is: /WEB-INF/views/Login.jsp

Solution

You are using send :

userName=test

And get the attribute with

request.getParameter("username");

You made a typo. Use instead

request.getParameter("userName");

Error you didn't do in the second part.

NOTE:

I suggest you define constant value for those instead of use a String literal

private final statis String USER_NAME = "userName";

And use it each time you need

request.getParameter(USER_NAME);

Answered By - AxelH