[AcceptVerbs(HttpVerbs.Post)]

         public ActionResult login(FormCollection form)

         {

             Session["login"] = "True";

             return Redirect("/Home/Index");

         }

         [IsLogin]

         public ActionResult Index()

         {

             return View();

         }

   //自定义过滤器

     public class IsLogin : ActionFilterAttribute

     {

         //当方法执行时

         public override void OnActionExecuting(ActionExecutingContext filterContext)

         {

             //base.OnActionExecuting(filterContext);

             try

             {  var sess=filterContext.RequestContext.HttpContext.Session["login"];

                 if (sess==null  ||sess.ToString()!="True")

                     filterContext.Result = new RedirectResult("/Home/login");

             }

             catch

             {

                 filterContext.Result = new RedirectResult("/Shared/Error");

             }

         }

         //当方法执行完毕

         public override void OnActionExecuted(ActionExecutedContext filterContext)

         {

             base.OnActionExecuted(filterContext);

         }

     }