Reloading JSP page

I have an authorization frame displayed on every page and I want to keep that page displaying even if the user will choose to log in (using jstl tags i will simply put instead of this frame user info and link to shopping cart). How can i achieve that ? I have some ideas, but they all breaking out my controller design.

public class FrontController extends HttpServlet {

private ActionContainer actionContainer = ActionContainer.getInstance();

public FrontController() {
    super();
}
/** 
 * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
 * @param request servlet request
 * @param response servlet response
 * @throws ServletException if a servlet-specific error occurs
 * @throws IOException if an I/O error occurs
 */
@SuppressWarnings("unchecked")
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

    String page = null;

    try {
        Action action = actionContainer.getAction(request);
        page = action.execute(request, response);
        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(page);
        dispatcher.forward(request, response);

    } catch (ActionNotFoundException e) {
        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(PageNames.ERR_PAGE);
        request.setAttribute(AttributeNames.ERR_MESSAGE_ATTRIBUTE, "Unknown Action command: " + e.getMessage());
        dispatcher.forward(request, response);
    } catch (Exception e) {
        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(PageNames.ERR_PAGE);
        request.setAttribute(AttributeNames.ERR_MESSAGE_ATTRIBUTE, "Exception:\n" + e.getMessage());
        dispatcher.forward(request, response);
    }
}

@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);
}

/** 
 * Returns a short description of the servlet.
 * @return a String containing servlet description
 */
@Override
public String getServletInfo() {
    return "Front Controller";
}

@Override
public void init() throws ServletException {
    super.init();
    Locale.setDefault(new Locale("ru","RU"));
}    

}

I was thinking about of redirecting to especially written for this case page, which will redirect to the original page, or to check 开发者_StackOverflow社区page string for null and reloading from controller the original page, but i cannot clearly understand how to do this.

Your question isn't clear enough. But I think you're asking how you can replace a certain component on a page (Login button) with an other (username, welcome message and shopping cart details) after the user logs in.

If I understand your requirements, then what I would do after the user logs in is set a cookie (or a value in localStorage). The cookie is added to the Set-Cookie response header by means of the addCookie method of HttpServletResponse. Here's an example:

  Cookie userCookie = new Cookie("user", "uid1234");
  response.addCookie(userCookie);

Then in your controller simply check if the "user" value is set or not and take the appropriate action. A tutorial on servlets with cookies.

If you need to handle the front-end component, and change values on the form without reloading the page, I would recommend using javascript to do this, you can find and remove the old DOM elements with new ones (User's name, Welcome message, shopping cart, whatever).

If your iFrame is doing the login, then on successful login, have it call a function in your top window that does the update after reading the updated values from the cookie.

If you want to handle this completely at the front-end, i.e. Javascript, then I would skip using cookies and use localStorage instead. There is plenty of help on Stackover and on the internet about what localStorage is, but I will suggest the YUI Storage Lite library which makes storing and loading data from localStorage very simple.

Regards,

Include the current URL as a hidden field of your authentication form. In the action handling the authentication, once the user is authenticated, redirect to this URL.

In the JSPs, test if the user is authenticated and include the authentication form or the shopping cart. This test can be done by just putting a boolean value in the HTTP session once the user is authenticated.