简单的限流过滤器

public class RateLimitFilter : ActionFilterAttribute    {        private const int MaxRequests = 30; //1分钟访问最大频率        private bool StartUp = true; //是否启用        public override void OnActionExecuting(ActionExecutingContext context)        {            if (StartUp)            {                base.OnActionExecuting(context);                string clientId = GetIP();                if (GetCache(clientId) == null)                {                    SetCacheRelativeTime(clientId, 1, 60);                }                else                {                    var cs = int.Parse(GetCache(clientId).ToString());                    SetCacheRelativeTime(clientId, cs += 1, 60);                }                //var x = int.Parse(GetCache(clientId).ToString());                if (int.Parse(GetCache(clientId).ToString()) > MaxRequests)                {                    //返回值规范不统一                    context.Result = new ContentResult { Content = "<script type='text/javascript'>alert('" + clientId + "  访问过于频繁,请稍等片刻!');</script><h1 style='text-align: center; color: red;'>" + clientId + "  访问过于频繁,请稍等片刻!<h1>" };
                    //返回值规范统一   前端有错误提示                    //context.Result = new JsonResult()                    //{                    //    Data = new { Result = false, status = false, suc = false, message = "" + clientId + "  访问过于频繁,请稍等片刻!" },                    //    JsonRequestBehavior = JsonRequestBehavior.AllowGet                    //};                }            }         }

        /// <summary>        /// 获取客户端IP地址        /// </summary>        /// <returns>若失败则返回回送地址</returns>        public static string GetIP()        {            //如果客户端使用了代理服务器，则利用HTTP_X_FORWARDED_FOR找到客户端IP地址            string userHostAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];            if (!string.IsNullOrEmpty(userHostAddress))            {                userHostAddress = HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString().Split(',')[0].Trim();            }            //否则直接读取REMOTE_ADDR获取客户端IP地址            if (string.IsNullOrEmpty(userHostAddress))            {                userHostAddress = HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];            }            //前两者均失败，则利用Request.UserHostAddress属性获取IP地址，但此时无法确定该IP是客户端IP还是代理IP            if (string.IsNullOrEmpty(userHostAddress))            {                userHostAddress = HttpContext.Current.Request.UserHostAddress;            }            //最后判断获取是否成功，并检查IP地址的格式（检查其格式非常重要）            if (!string.IsNullOrEmpty(userHostAddress) && IsIP(userHostAddress))            {                return userHostAddress;            }            return "127.0.0.1";        }
        /// <summary>        /// 检查IP地址格式        /// </summary>        /// <param name="ip"></param>        /// <returns></returns>        public static bool IsIP(string ip)        {            return System.Text.RegularExpressions.Regex.IsMatch(ip, @"^((2[0-4]\d|25[0-5]|[01]?\d\d?)\.){3}(2[0-4]\d|25[0-5]|[01]?\d\d?)$");        }
        #region  设置相对过期时间Cache值(即:访问激活后不过期)        /// <summary>                /// 设置相对过期时间Cache值(即:访问激活后不过期)        /// </summary>                /// <param name="objectkey"></param>                /// <param name="objObject"></param>                /// <param name="timeSpan">超过多少时间不调用就失效，单位是秒</param>        
        public static void SetCacheRelativeTime(string objectkey, object objObject, int timeSpan)        {            System.Web.Caching.Cache objCache = HttpRuntime.Cache;            objCache.Insert(objectkey, objObject, null, DateTime.MaxValue, TimeSpan.FromSeconds(timeSpan));        }        #endregion
        #region  获取当前应用程序指定CacheKey的Cache值        /// <summary>        /// 获取当前应用程序指定CacheKey的Cache值        /// </summary>        /// <param name="CacheKey"></param>        /// <returns></returns>y        public static object GetCache(string CacheKey)        {            try            {                System.Web.Caching.Cache objCache = HttpRuntime.Cache;                Object value = objCache[CacheKey];                if (value != null)                {                    return value;                }                else                {                    return null;                }            }            catch (Exception)            {                return null;            }
        }        #endregion    }

public class FilterConfig {        public static void RegisterGlobalFilters(GlobalFilterCollection filters)        {            filters.Add(new RateLimitFilter()); // 过滤器        } }

protected void Application_Start(){            AreaRegistration.RegisterAllAreas();            RouteConfig.RegisterRoutes(RouteTable.Routes);            BundleConfig.RegisterBundles(BundleTable.Bundles);            UnityConfig.RegisterComponents();
            // 注册全局过滤器            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
}