final FormPanel formPanel = new FormPanel();
        formPanel.setEncoding(FormPanel.ENCODING_URLENCODED);
        formPanel.setMethod(FormPanel.METHOD_POST);

        VerticalPanel verticalPanel = new VerticalPanel();
        verticalPanel.add(new Label("Username"));
        TextBox userid = new TextBox();
        userid.setName("username");
        verticalPanel.add(userid);

        verticalPanel.add(new Label("Password"));
        PasswordTextBox passwd = new PasswordTextBox();
        passwd.setName("password");
        verticalPanel.add(passwd);

        verticalPanel.add(new Button("Submit", new ClickHandler() {

            @Override
                public void onClick(ClickEvent event) {
            formPanel.submit();
            }
        }));

        formPanel.add(verticalPanel);

        formPanel.setAction("/login");

        formPanel.addSubmitHandler(new FormPanel.SubmitHandler() {
            public void onSubmit(SubmitEvent event) {
            }
        });
        formPanel.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
            public void onSubmitComplete(SubmitCompleteEvent event) {
                GWT.log(event.getResults());
            }
        });

        RootPanel.get().add(formPanel);

@Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        resp.setContentType("text/plain");

        System.out.println("Login request for " + username + " / " + password);
        if (username.equals("test1234")) {
            // send test response to output
            printMessageToOutputStream(resp, "OK", true, true);
        }
        else {
            printMessageToOutputStream(resp, "NOK", false , true);
        }
    }