直接贴代码：

第一步：判断如果Sessoin为空，返回前台信息（红色代码）

protected override void OnActionExecuting(ActionExecutingContext filterContext)
{

if (HttpContext.Request.Url.ToString().IndexOf("ValidCode") != -1
|| HttpContext.Request.Url.ToString().IndexOf("Login") != -1)
{
base.OnActionExecuting(filterContext);
return;
}


if (CurMemberCache.Id == 0 && HttpContext.Request.Url.ToString().ToLower().IndexOf("loginpage") == -1)
{
if (filterContext.HttpContext.Request.IsAjaxRequest())
{

//Session为空时，返回为空的报错信息
Response.AppendHeader("sessionstatus","zhongtouhangsettionTimeout");
Response.End();
}
else
{
filterContext.Result = RedirectToAction("LoginPage","HomeDesk",new { url = Request.Url.ToString().ToLower() });
}
}
else
{
if ((Session["AllowNid"] == null || Convert.ToInt32(Session["AllowNid"]) != CurNavigationId)
&& HttpContext.Request.Url.ToString().IndexOf("CommonPage") == -1
&& HttpContext.Request.Url.ToString().IndexOf("HomeDesk") == -1)
{
filterContext.Result = RedirectToAction("ErJiPwdPage","CommonPage",new { url = Request.Url.ToString().ToLower() });
}
base.OnActionExecuting(filterContext);
}

｝

第二步，修改jQuery的Ajax方法，代码如下：

function done(status,nativeStatusText,responses,headers) { //TODO:修改jQuery，当Ajax请求时，如果Session已过期，那么，跳转到登录页 if (headers.indexOf("zhongtouhangsettionTimeout") != -1) { alert("登录超时，请重新登录！"); window.location = '/HomeDesk/LoginPage'; return null; }