jQuery getJSON方法没有响应

我试图在我的网页上创建一个登录操作，这应该调用servlet传递它所需的参数，并返回一个JSON对象到浏览器。为此，我使用jQuery的$. getjson()方法。

这是我的登录表单的HTML -

<form class="form" method="post" id="loginFrm" name="loginFrm">
    <div class="form-group">
       <label for="username">Email</label>
             <input name="email" id="email" type="text" placeholder="Email" style="color: black;">
                                </div>
         <div class="form-group">
            <label for="password">Password</label>
            <input name="password" id="password" type="password" placeholder="Password" style="color: black;"><br>
         <span class="text-danger" id="error-box"></span>
    </div>
       <button id="btnLogin" class="btn btn-primary" style="margin-top: 17px;">Login</button>
 </form>

下面是在点击登录按钮时执行的JavaScript代码-

// Add an onlick handler to the login button
$('#btnLogin').on('click', loginAction);

function loginAction()  {
var userEmail = $('#email').val();
var userPassword = $('#password').val();
if (userEmail == "")    {
    $('#error-box').html("Please enter your email");
    $('#email').focus();
    return false;
}
if (userPassword == "") {
    $('#error-box').html("Please enter your password");
    $('#password').focus();
    return false;
}
var credentials = $('#loginFrm').serialize();
// alert(credentials);
var url = "/login?" + credentials;
$.getJSON(url, function (data)  {
    alert("Inside getJSON callback method");
    alert(data);
});
}

同样，这里是来自LoginServlet的代码。 Servlet被映射到URL模式-/login

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    logger.info("Inside LoginServlet");
    response.setContentType("application/json");
    String email = request.getParameter("email") == null ? "" : request.getParameter("email");
    String password = request.getParameter("password") == null ? "" : request.getParameter("password");
    logger.info("email:: " + email + " password::" + password);
    Customer customer = null;
    Developer developer = null;
    JsonObjectBuilder objBuilder = Json.createObjectBuilder();
    JsonObject responseObject = null;
    PrintWriter pout = response.getWriter();
    if (!email.equals("") && !password.equals("")) {
        boolean loginSuccess = false;
        logger.info("Trying to load customer entity");
        customer = ofy().load().key(Key.create(Customer.class, email)).now();
        if (null == customer) {
            logger.info("customer entity not found. Trying to load developer entity");
            developer = ofy().load().key(Key.create(Developer.class, email)).now();
            if (developer != null) {
                logger.info("developer entity found");
                if (developer.getPassword().equals(password)) {
                    logger.info("Developer login successful");
                    loginSuccess = true;
                    responseObject = objBuilder.add("status", "success").add("userType", "developer").add("forwardUrl", "Home.jsp").build();
                    logger.info("JsonObject constructed as:: " + responseObject);
                    pout.println(responseObject.toString());
                    pout.flush();
                    // request.getRequestDispatcher("Home.jsp").forward(request, response);
                }
            }
        } else {
            if (customer.getPassword().equals(password)) {
                logger.info("Customer login successful");
                loginSuccess = true;
                responseObject = objBuilder.add("status", "success").add("userType", "customer").add("forwardUrl", "Home.jsp").build();
                logger.info("JsonObject constructed as:: " + responseObject);
                pout.println(responseObject.toString());
                pout.flush();
                // request.getRequestDispatcher("Home.jsp").forward(request, response);
            }
        }
        if (!loginSuccess) {
            // Login Failure
            responseObject = objBuilder.add("status", "faliure").build();
            logger.info("Login Faliure. JsonObject constructed as:: " + responseObject);
            pout.println(responseObject.toString());
            pout.flush();
        }
    }
}

我的问题是Servlet似乎没有返回对getJSON()的响应。 Firefox的网络选项卡没有显示来自请求的任何响应。它甚至不打印请求的HTTP状态码

然而，我确实知道请求正在到达LoginServlet，从以下日志中可以看出-

[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doGet
[INFO] INFO: Request inside doGet method. Calling doPost with it
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: Inside LoginServlet
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: email:: prateekmathur1991@gmail.com password::prateek
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: Trying to load customer entity
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: customer entity not found. Trying to load developer entity
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: developer entity found
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: Developer login successful
[INFO] Jul 20, 2015 10:42:13 PM com.allissues.logic.LoginServlet doPost
[INFO] INFO: JsonObject constructed as:: {"status":"success","userType":"developer","forwardUrl":"Home.jsp"}

但是来自AJAX请求的响应是空的，我很难理解我的代码在哪里出错了。

编辑此外，当我访问这个URL从网页-http://localhost: 8080/登录?电子邮件= prateekmathur1991@gmail.com&密码= prateek

它给了我正确的JSONObject我期待-{"状态":"成功","userType":"开发人员","forwardUrl":"Home.jsp"}