Login过滤器

继承自ActionFilterAttibute

 public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            //HttpContext.Current.Response.Write("OnActionExecuting:正要准备执行Action的时候但还未执行时执行<br />");    
            if (HttpContext.Current.Session["admin"] == null)
            {
                HttpContext.Current.Response.Write("<script>alert('请登录！');window.parent.location.href='/Admin/Login'</script>");
                HttpContext.Current.Response.End();
                return;
            }
        }