ASP.NET MVC4 自定义授权

我通过覆盖AuthorizeAttribute来执行自定义授权，在 ASP.NET MVC4 中实现了自定义授权属性。我想在某些控制器和控制器操作上实现这一点，以使它们拒绝未经授权的请求，例如未登录 and/or 某些权限问题的用户。我不想实现 asp.net 成员资格和授权，代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Diagnostics.CodeAnalysis;
using System.Security.Principal;
using System.Web.Mvc.Properties;
using System.Web.Routing;

namespace TestMVC4
{
    public sealed class AuthorizeUserAttribute : AuthorizeAttribute
    {
        private static readonly string[] _emptyArray = new string[0];
        string activities;
        string[] activitiesList = _emptyArray;

        string roles;
        string[] rolesList = new string[0];

        /// <summary>
        /// Gets or sets list of authorized activities 
        /// </summary>
        public string Activities
        {
            get { return activities ?? String.Empty; }
            set
            {
                activities = value;
                activitiesList = SplitString(value);
            }
         }

         public string CRole
         {
            get { return roles ?? String.Empty; }
            set
            {
                 roles = value;
                 rolesList = SplitString(value);
             }
         }

        /// <summary>
        /// Authorization initial call
        /// </summary>
        /// <param name="filterContext">Filter context</param>
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            if (filterContext == null)
            {
                throw new ArgumentNullException("filterContext");
            }

            if (OutputCacheAttribute.IsChildActionCacheActive(filterContext))
            {
                // If a child action cache block is active, we need to fail immediately, even if authorization
                // would have succeeded. The reason is that there's no way to hook a callback to rerun
                // authorization before the fragment is served from the cache, so we can't guarantee that this
                // filter will be re-run on subsequent requests.
                //throw new InvalidOperationException(MvcResources.AuthorizeAttribute_CannotUseWithinChildActionCache);
                throw new InvalidOperationException("Cannot use within child action cache.");
            }

            bool skipAuthorization = filterContext.ActionDescriptor.IsDefined(typeof(AllowAnonymousAttribute), inherit: true)
                                     || filterContext.ActionDescriptor.ControllerDescriptor.IsDefined(typeof(AllowAnonymousAttribute), inherit: true);

            if (skipAuthorization)
            {
                return;
            }

            if (AuthorizeCore(filterContext.HttpContext))
            {
                // ** IMPORTANT **
                // Since we're performing authorization at the action level, the authorization code runs
                // after the output caching module. In the worst case this could allow an authorized user
                // to cause the page to be cached, then an unauthorized user would later be served the
                // cached page. We work around this by telling proxies not to cache the sensitive page,
                // then we hook our custom authorization code into the caching mechanism so that we have
                // the final say on whether a page should be served from the cache.

                HttpCachePolicyBase cachePolicy = filterContext.HttpContext.Response.Cache;
                cachePolicy.SetProxyMaxAge(new TimeSpan(0));
                cachePolicy.AddValidationCallback(CacheValidateHandler, null /* data */);
            }
            else
            {
                HandleUnauthorizedRequest(filterContext);
            }
        }

        /// <summary>
        /// Main method for overriding custom authorization for application
        /// </summary>
        /// <param name="httpContext">Current execution context</param>
        /// <returns>True/False whether user is authorized for given activity or not respectively</returns>
        protected override bool AuthorizeCore(HttpContextBase httpContext)
        {
            if (httpContext == null)
            {
                throw new ArgumentNullException("httpContext");
            }

            //Verify sessionuser roles
            if (rolesList != null)
            {
                String sessionRole = Convert.ToString(httpContext.Session["MyRole"]);

                foreach (String role in rolesList)
                {
                    if (role == sessionRole)
                        return true;
                }
            }

            //IPrincipal user = httpContext.User;
            //if (!user.Identity.IsAuthenticated)
            //{
            //    return false;
            //}

            //if (_usersSplit.Length > 0 && !_usersSplit.Contains(user.Identity.Name, StringComparer.OrdinalIgnoreCase))
            //{
            //    return false;
            //}

            //if (_rolesSplit.Length > 0 && !_rolesSplit.Any(user.IsInRole))
            //{
            //    return false;
            //}

            return false;
        }

        /// <summary>
        /// Overriden method for handling unauthorized request routing
        /// </summary>
        /// <param name="filterContext">Authorization context for which the request has been made</param>
        protected override void HandleUnauthorizedRequest(AuthorizationContext filterContext)
        {
            // Returns HTTP 401 - see comment in HttpUnauthorizedResult.cs.
            filterContext.Result = new HttpUnauthorizedResult();

            //filterContext.RequestContext.RouteData;

            //filterContext.Result = new RedirectToRouteResult(
            //        new RouteValueDictionary(
            //            new
            //            {
            //                controller = "Error",
            //                action = "Unauthorised"
            //            })
            //        );
        }

        private void CacheValidateHandler(HttpContext context, object data, ref HttpValidationStatus validationStatus)
        {
            validationStatus = OnCacheAuthorization(new HttpContextWrapper(context));
        }

        protected HttpValidationStatus OnCacheAuthorization(HttpContextBase httpContext)
        {
            if (httpContext == null)
            {
                throw new ArgumentNullException("httpContext");
            }

            bool isAuthorized = AuthorizeCore(httpContext);
            return (isAuthorized) ? HttpValidationStatus.Valid : HttpValidationStatus.IgnoreThisRequest;
        }

        /// <summary>
        /// Splits the string on commas and removes any leading/trailing whitespace from each result item.
        /// </summary>
        /// <param name="original">The input string.</param>
        /// <returns>An array of strings parsed from the input <paramref name="original"/> string.</returns>
        string[] SplitString(string original)
        {
            if (String.IsNullOrEmpty(original))
            {
                return _emptyArray;
            }

            var split = from piece in original.Split(',')
                        let trimmed = piece.Trim()
                        where !String.IsNullOrEmpty(trimmed)
                        select trimmed;
            return split.ToArray();
        }
      }
}

在调用OnAuthoriztion方法之前一切正常。问题是我的自定义属性activities和roles以及所有其他变量都为空或无效我不明白为什么会发生这种情况。所有这些变量都会被初始化，但是当它们到达OnAuthorization函数时它们都会变为空白。