C# MVC4 执行特性之后不再执行Action

 1                     string returnUrl = HttpContext.Current.Request.Url.PathAndQuery;
 2                     var url = FormsAuthentication.LoginUrl + "?returnUrl=" + HttpUtility.UrlEncode(returnUrl);
 3                     //HttpContext.Current.Response.Redirect(url, true);//进入action
 4                     //filterContext.HttpContext.Response.Redirect(url);//进入action
 5                     /*filterContext.Result = new RedirectToRouteResult( //不进入action
 6                     new RouteValueDictionary
 7                     {
 8                         { "action", "Login" },
 9                         { "controller", "Admin" },
10                         {"returnUrl", returnUrl}
11                     });*/
12                     filterContext.Result = new RedirectResult(url);//不进入action，转到登录页面。