Redirect to login page after session timeout

问题:

I have found some similar questions but none gave me what I really need.

Here is the thing, I have added this to my web.config to handle user session expiration:

<sessionState mode="InProc" timeout="1" />

After 1 minute, the Session_End event from Global.asax is raised:

Sub Session_End(ByVal sender As Object, ByVal e As EventArgs)
    Response.Redirect("Login.aspx")
End Sub

This doesn't work, because:

Response is not available in this context.

(By the way, this question got an anwswer telling that this is ok and it got upvotes).

I don't want nothing fancy. I just want a simple way to redirect the user to the login page when the session time expires. That's all.

Thank you.

回答1:

Session_End is a server-side event, meaning it is triggered on the web server and has nothing to do with a request by the client. This is why the Request is unavailable.

You have two choices in this matter:

1. On each client request, check if a specific Session variable is set. If it is not, it means the previous Session has expired and the new Session must be populated. (I am assuming this is why you want to check for Session expiration)

2. Have a javascript call on the client that periodically goes back to the server to check if the Session is still valid. If the Session has expired, you can warn the user that their Session is about to expire.

HTH

回答2:

Description

You can use the Page_Initevent in the global.asax

Sample

Protected Sub Page_Init(sender As Object, e As EventArgs)
 If Context.Session IsNot Nothing Then
  If Session.IsNewSession Then
   Dim newSessionIdCookie As HttpCookie = Request.Cookies("ASP.NET_SessionId")
   If newSessionIdCookie IsNot Nothing Then
    Dim newSessionIdCookieValue As String = newSessionIdCookie.Value
    If newSessionIdCookieValue <> String.Empty Then
     ' This means Session was timed Out and New Session was started
     Response.Redirect("Login.aspx")
    End If
   End If
  End If
 End If
End Sub

More Information

• Detecting Session Timeout And Redirect To Login Page In ASP.NET

回答3:

Check for expired sessions on every Page_Init event. If there are too many pages to do this check, this is what I usually do:

• I create a base class and inherit from System.Web.UI.Page.
• Write my redirect logic in the Page_Init event of my base class.
• Have the rest of my pages inherit from this base class.

Good luck.

回答4:

protected void Page_Init(object sender, EventArgs e)
{
    if (Context.Session != null)
    {
        if (Session.IsNewSession)
        {
            HttpCookie newSessionIdCookie = Request.Cookies["ASP.NET_SessionId"];
            if (newSessionIdCookie != null)
            {
                string newSessionIdCookieValue = newSessionIdCookie.Value;
                if (newSessionIdCookieValue != string.Empty)
                {
                    // This means Session was timed Out and New Session was started
                    Response.Redirect("Login.aspx");
                }
            }
        }
    }
}