public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

    String user = req.getParameter("usern");
    String password = req.getParameter("psd");

    HttpSession s = req.getSession();
    s.setAttribute("usernm", user);

    if ((user.equalsIgnoreCase(????) && password.equalsIgnoreCase(????))) {
        req.getRequestDispatcher("/profile").include(req, res);
    } else {
        out.print("Sorry UserName or Password Error!");
        req.getRequestDispatcher("/index.html").forward(req, res);

    }

}

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

    String n = req.getParameter("userName");
    String p = req.getParameter("userPass");
    String c = req.getParameter("confirmPass");
    String e = req.getParameter("userEmail");

    if (!c.equals(p)) {
        out.println("<h3>Enter correct password</h3>");
        req.getRequestDispatcher("register.html").forward(req, res);
    } else {

        Entity u = new Entity("User", e);
        u.setProperty("userName", n);
        u.setProperty("passWord", p);
        u.setProperty("userEmail", e);
        DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
        datastore.put(u);

        u.getKey().getName();
        com.google.appengine.api.datastore.Key k = KeyFactory.createKey("User", e);

        out.println("<h3>Successfully registered</h3>");
    }
}