c# - session 过期并抛出异常

Question

我对 session 过期有疑问。首先，它每 20 分钟过期一次，并抛出一个错误...

我尝试通过以下方式修复它:

if (Session["userName"].ToString() == null)
{
   Session.RemoveAll();
   Response.Redirect("~/Login.aspx?sessionError=" + "*Session Expired on pageload PleaseLog in again");
}

但是我得到以下错误:

Object reference not set to an instance of an object.

我的堆栈跟踪是:

[NullReferenceException: Object reference not set to an instance of an object.] copiunGUI.Site1.checksession() in C:\Users\jagmit\Documents\Visual Studio 2008\Projects\copiunGUI\copiunGUI\Site1.Master.cs:224 copiunGUI.Site1.TreeViewMain_Unload(Object sender, EventArgs e) in C:\Users\jagmit\Documents\Visual Studio 2008\Projects\copiunGUI\copiunGUI\Site1.Master.cs:210 System.Web.UI.Control.OnUnload(EventArgs e) +8681754 System.Web.UI.Control.UnloadRecursive(Boolean dispose) +252 System.Web.UI.Control.UnloadRecursive(Boolean dispose) +188 System.Web.UI.Control.UnloadRecursive(Boolean dispose) +188 System.Web.UI.Control.UnloadRecursive(Boolean dispose) +188 System.Web.UI.Control.UnloadRecursive(Boolean dispose) +188 System.Web.UI.Page.UnloadRecursive(Boolean dispose) +23 System.Web.UI.Page.ProcessRequestCleanup() +43

我的 web.config 是:

<authentication mode="Forms">
    <forms loginUrl="Login.aspx" defaultUrl="~/Default.aspx" name="Cookie" timeout="10080" path="/">
    </forms>
</authentication>
<authorization>
    <deny users="?"/>
    <allow users="*"/>
</authorization>

请帮忙......

谢谢

感谢你们的输入...

我试过这个:

if (Session["userName"] == null)
{
   Session.RemoveAll();
   Response.Redirect("~/Login.aspx?sessionError=" + "*Session Expired on pageload PleaseLog in again");
}

但是我得到了错误:

Response is not available in this context.

Answer 1

问题出在这里:

if (Session["userName"].ToString() == null)

当 Session["UserName"] 是一个空对象引用时，您不能正确地对其调用 .ToString()。

试试这个...

if (Session["userName"] == null)...