@Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String url = "/index.html"; // get current action String action = request.getParameter("action"); if (action == null) { action = "join"; // default action } // perform action and set URL to appropriate page if (action.equals("join")) { url = "/index.jsp"; // the "join" page } else if (action.equals("add")) { // get parameters from the request String firstName = request.getParameter("firstName"); String lastName = request.getParameter("lastName"); String email = request.getParameter("email"); // store data in User object User user = new User(); user.setEmail(email); user.setFirstName(firstName); user.setLastName(lastName); // validate the parameters String message; if (UserDB.emailExists(user.getEmail())) { message = "This email address already exists.<br>" + "Please enter another email address."; url = "/index.jsp"; } else { message = ""; url = "/thanks.jsp"; UserDB.insert(user); } request.setAttribute("user", user); request.setAttribute("message", message); } getServletContext().getRequestDispatcher(url).forward(request, response); }