Question

最终编辑：我实际上使用的是log4j并且配置不佳导致它对每个LOGGER.debug（）进行双重记录;

我无法弄清楚为什么我的servlet正在为我的前端发送的每个ajax调用接收2个请求。

我用Tomcat运行我的Servlet。

当我将自己与前端连接时，我的System.out.println（）打印“Hello”两次。

我在Firefox中使用F12多次验证，我只发送一个参数action = register的ajax请求。

我的HttpServlet：

@WebServlet(name = "MyServlet", urlPatterns = { "/actions" })

public class MyServlet extends HttpServlet {

private static final long serialVersionUID = -983728805534985870L;



public MyServlet() {

}



protected void doPost(HttpServletRequest request, HttpServletResponse response)

        throws ServletException, IOException {

    response.setHeader("Access-Control-Allow-Origin", "*");

    response.setHeader("Access-Control-Allow-Methods", "GET,POST");

    response.setCharacterEncoding("UTF-8");

    response.setContentType("text/html");



    switch (request.getParameter("action")) {

    case "call":

        callAction(request, response);

        break;

    case "register":

        System.out.println("Hello");

        register(request, response);

        break;

    case "unregister":

        unregister(request, response);

        break;

    }

}



private void callAction(HttpServletRequest request, HttpServletResponse response) {

    /*
    ...
    */

}

private void register(HttpServletRequest request, HttpServletResponse response) {

    String connectedUserNumber = request.getParameter("number");

    String uniqueID = agentUCC.register(connectedUserNumber);

    LOGGER.debug("Register request from " + request.getRemoteAddr() + " with phone number " + connectedUserNumber);

    LOGGER.info("User with phone number [{}] has been connected with uniqueID [{}]", connectedUserNumber, uniqueID);

    handleSuccess(response, uniqueID);

}



private void unregister(HttpServletRequest request, HttpServletResponse response) {

    /*
    ...
    */

}



// utility method - avoid code redundancy

private void handleSuccess(HttpServletResponse response, String message) {

    response.setStatus(HttpServletResponse.SC_OK);

    response.setHeader("Access-Control-Allow-Origin", "*");

    try {

        response.getWriter().print(message);

    } catch (IOException e) {

        LOGGER.error("ERROR : {}", e.getMessage(), e);

    }

}

}

我正在用一个简单的前端测试它：

    <!doctype html>
<html>
<head>
  <meta charset="utf-8">
</head>
<body>
    <!--  This will be displayed first. When the user isn't logged yet. -->
    <div id="connectionPage">
        <h2>Connection</h2>
        <br/>
        <p>Your phone number :</p>
        <input type="text" id="connectionNumber"/>
        <br/><br/>
        <input type="button" value="Connect" id="connect"/>
        <br/>
        <p id="connectionError"></p>
    </div>

    <!-- 
        ...
    -->

    <script src="resources/js/jquery-3.3.1.min.js"></script>
    <script src="resources/js/script.js"></script>
</body>
</html>

和我的script.js：

$(function() {
    var connectedUserNumber;    
    // session's ID
    var uniqueID;

    // Connection
    $("#connect").click(function(){
        connectedUserNumber = $("#connectionNumber").val();
        register();
    });

    // Register to the back-end
    function register(){
        console.log("Register !");
        $.ajax({
            xhrFields: {
                withCredentials: false
            },
            type: 'POST',
            url: 'foo/actions',
            data: 'action=register&number=' + connectedUserNumber,
            datatype: 'text',
            success: function(data) {
                uniqueID = data;
                doPoll();
            },
            error: function(jqXHR, textStatus, exception) {
               /*
            ...
           */
            }
        });
    }

    // Send every 2 seconds an ajax's request to retrieve incoming call's notifications
    function doPoll() {
        $.ajax({
            type: 'POST',
            url: 'foo/actions',
            data: 'action=getNotificationToPush&uniqueID=' + uniqueID,
            datatype: 'json',
            success: function(data) {
                handleDoPollSuccess(data);
            },
            error: function(jqXHR, textStatus, exception) {
                handleEventError(jqXHR, textStatus, exception);
            }
        }).always(function() {
            // Waits 2 seconds before sending the next request
            setTimeout(doPoll, 2000);
        });
    }
    /*
    ...
       */
});

你们是否知道这可能来自哪里？如果需要，我可以提供更多细节。

编辑：我在我的JS文件中按ctrl + f +“register（）”，我调用此方法的唯一地方是第9行。无论如何，我会在Firefox调试控制台中看到第二个ajax调用。

编辑之二：两个请求都在相同的千分之一秒内收到。（例如：两者均于14：40：30：859收到）

HttpServlet为每个ajax调用接收2个请求

0 个答案: