web流量控制简化处理类

web流量控制简化处理类

该类可用于HttpListener类的web端或asp.net web服务端的访问控制，类代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Utility;

namespace My.BLL.Throttle
{
    /// <summary>
    /// 访问次数检验类
    /// 自动清理过期的用户数据不及时，处理不合理
    /// </summary>
    public class ThrottlingHandler
    {
        private  static IThrottleStore _store;
        private static TimeSpan _period;
        private static int _maxRequests;
        
        static readonly Log Log = new Log("Bll");


        static ThrottlingHandler()
        {
            _store = new InMemoryThrottleStore();
            _period = TimeSpan.FromSeconds(60);
        }

        /// <summary>
        /// 设置1分钟内用户的最大访问次数
        /// </summary>
        /// <param name="maxRequests"></param>
        public static void SetMaxReuest(int maxRequests)
        {
            _maxRequests = maxRequests;
        }

        /// <summary>
        /// 校验用户1分钟内是否超过最大访问次数限制
        /// </summary>
        /// <param name="identifier">用户标识符</param>
        /// <returns></returns>
        public static bool IsOverVisitLimit(string identifier)
        {
            //条目大于5000时清除所有数据,这里的处理不当，先将就这么处理，应定时检测过期的条目，清除过期的
            if (_store.GetCount() > 5000)
            {
                _store.Clear();
            }
            ThrottleEntry entry = null;
            if (_store.TryGetValue(identifier, out entry))
            {
                if (entry.PeriodStart + _period < DateTime.UtcNow)
                {
                    _store.Rollover(identifier);
                }
            }

            _store.IncrementRequests(identifier);
            if (!_store.TryGetValue(identifier, out entry))
            {
                return false;
            }

            if (entry.Requests > _maxRequests)
            {
                Log.Info(identifier + " 访问次数超限 " + _maxRequests.ToString());
                return true;
            }
            return false;
        }
    }
}

该类内部调用的类参见 

调用如下：

BLL.Throttle.ThrottlingHandler.SetMaxReuest(Global.ThrottleMaxRequestTimes);
if (Global.IsEnableThrottle == "1")
{
  var isOverVisit = BLL.Throttle.ThrottlingHandler.IsOverVisitLimit(ip);
  if (isOverVisit)
  {
    // 构造回应内容
    string responseString
      = "访问太频繁了";
    // 设置回应头部内容，长度，编码
    response.ContentLength64
      = Encoding.UTF8.GetByteCount(responseString);
    response.ContentType = "text/html; charset=UTF-8";
    // 输出回应内容
    Stream output2 = response.OutputStream;
    StreamWriter writer = new StreamWriter(output2);
    writer.Write(responseString);
    // 必须关闭输出流
    writer.Close();
    return;
  }
}

--- end ---