警告和扩展用户会话

我使用基本的身份验证为我的网站，有一个问题，当用户在一个表单上，需要一段时间来填写，他们的会话可能结束，并在点击"保存"的工作将消失，因为他们的会话不再有效。

我试了如下:

在web.config:

中设置会话超时时间为1分钟

<system.web>
<sessionState timeout="1"></sessionState>

将以下javascript添加到我的页面，它应该每30秒扩展一次会话:

AlertTimeOut = 30000; // Milliseconds, Alert Message       
WarnTimeOut = 30000; //  Warn Message before 30 sec of session out
setTimeout("WarnUser();", WarnTimeOut);
//setTimeout("AlertUser();", AlertTimeOut);
function AlertUser() {
    alert('Your session has been expired, please save your data outside the system [copy the data in word document].');
}
function WarnUser() {
    var currentTime = new Date()
    var hours = currentTime.getHours()
    var minutes = currentTime.getMinutes()
    if (minutes < 10) {
        minutes = "0" + minutes
    }
    if (hours > 11) {
        var tempTime = hours + ":" + minutes + "PM"
    } else {
        var tempTime = hours + ":" + minutes + "AM"
    }
    var ans = confirm("Your login session is about to expire in 5 minutes.Do you want to extend it? - Date: " + tempTime);
    if (ans) {
        var oImage = new Image;
        oImage.src = "tempdummy.gif" + Math.random();
        setTimeout("WarnUser();", WarnTimeOut);
    }
    else {
        setTimeout("AlertUser();", AlertTimeOut);
    }
}

这是我的main.aspx.cs页面的一个片段，在等待javascript弹出2次后，我刷新页面，是的，session["userid"]是null。我调试了javascript，它确实像它应该的那样击中了每一行代码。

protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["userid"] == null)
        {
           // the session is no longer valid, i guess the javascript didn't work :(
            //redirect user to an error page
        }
        else
         {
                username = (string)Session["userid"];
                // check user permission, and populate the form here
         }
     }

我在网上找到了一些使用类似代码的例子:

var oImage = new Image;
oImage.src = "tempdummy.gif" + Math.random();

扩展会话，但我想我只是不明白它是如何工作的。这是一个图像，我应该有在我的aspx页面的某个地方?它是如何工作的?因为它不适合我

---- || ---- || ---- || ---- || ---- || ---- || ---- ||

更新:

我还尝试了以下操作:

创建了一个refresh_session。只有一行代码的Aspx页面:

protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write("success");
    }

然后尝试POST到该页面以刷新会话(根据本文:http://naspinski.net/post/Automatically-refresh-your-users-Session-behind-the-scenes-using-jQuery-and-AspNet.aspx)

我更新的javascript看起来像:

    AlertTimeOut = 30000; // Milliseconds, Alert Message       
    WarnTimeOut = 30000; //  Warn Message before 30 sec of session out
    setTimeout("WarnUser();", WarnTimeOut);
    function TimedOut() {
        $.post("refresh_session.aspx", null,
        function (data) {
            if (data == "success") {
               setTimeout("TimedOut();", WarnTimeOut);
alert('refreshed');
            }
            else { alert('not refreshed'); }
        }
      );
    }
    function AlertUser() {
        alert('Your session has been expired, please save your data outside the system [copy the data in word document].');
    }
    function WarnUser() {
        var ans = confirm("Your login session is about to expire in 5 minutes.Do you want to extend it? ");
        if (ans) {
            var oImage = new Image;
            oImage.src = "tempdummy.gif";
            TimedOut() ;
            setTimeout("WarnUser();", WarnTimeOut);
        }
        else {
            setTimeout("AlertUser();", AlertTimeOut);
        }
    }

在frefresh_session的断点被击中，但是当我刷新我的页面时，它仍然是NULL在我的默认值。aspx :((((((

var oImage = new Image;
oImage.src = "tempdummy.gif" + Math.random();