HttpWebRequest 对象池 HTTP协议 HttpWebRequest和 Socket的一点总结

相信接触过网络开发的人对HTTP、HttpWebRequest、Socket这些东西都不陌生吧。它们之间的一些介绍和关系我这里都忽略了。开我们平时开发过程中也是很少有机会接触大什么大并发这个东东，一般大并发我们都需要考虑异步和多线程以及对象池，这个我们以一个简单demo来讲解吧。

主要的调用关系图如下：

类的结构图如下：

一：这里我们依次对这些类做一个简单的说明

HttpRequestInfo：

public string Url：http请求的url字符串，如http://www.baidu.com/
public byte[] PostData：Post请求中的数据
public WebHeaderCollection Headers：请求的头部数据
public bool AllowAutoRedirect ：是否允许301、302自动跳转，如果你想获取请求返回的头部信息，建议一般设置为false
public Dictionary<string, string> ExternalData ：请求过程中附加的数据（如数据记录的ID），便于在成功或失败回调函数中调用
public Action<HttpContextInfo> ActionCompleted ：请求成功后所调用的函数
public Action<HttpRequestException> ActionException：请求失败所调用函数
public HttpRequestInfo Clone()：返回当前对象的一个副本。

HttpResponseInfo：

public Stream ResponseContent ：Http请求返回内容（除头部信息）的对象流
public HttpStatusCode StatusCode：Http返回的状态
public string StatusDescription ：Http状态描述
public WebHeaderCollection Headers：Http返回的头部信息
public string GetString(Encoding coding)：把http返回体中数据流转换为字符串，转换编码就是我们所传参数。

   public interface IHttpRequest
    {
        void GetResponseAsync(HttpRequestInfo request);
        bool IsBusy { set; get; }
    }

在IHttpRequest接口中，IsBusy属性主要是判断当前对象是否正在使用中，GetResponseAsync方法是真正完成Http请求的方法。

这里我们主要看看HttpRequestFactory的封装吧，管理对象实例的个数，相当于一个对象池，这里的代码主要是基于。net framework2.0的，

首先我们需要2个集合分别管理HttpRequestInfo请求实例和IHttpRequest处理请求实例，

  static Queue<HttpRequestInfo> requestTask = new Queue<HttpRequestInfo>();
   static List<IHttpRequest> Handlers = new List<IHttpRequest>();

而我们暴露给外部的一个主要方法就是AddRequestTask，

  public static void AddRequestTask(HttpRequestInfo info)
        {
            if (!string.IsNullOrEmpty(info.Url))
            {
                lock (Lockobj)
                {
                    Interlocked.Increment(ref requestCount);
                    requestTask.Enqueue(info);
                }
            }
        }
那么这些请求在什么时候被处理了，在一个叫Process方法中处理，

private static void Process(object obj)
        {
            while (true)
            {
                IHttpRequest handler = GetAvailableHttpRequest();
                while (handler == null)
                {
                    Thread.Sleep(100);
                    handler = GetAvailableHttpRequest();
                }
                HttpRequestInfo task = GetTask();
                while (task == null)
                {
                    Thread.Sleep(100);
                    task = GetTask();
                }
                if (task != null && handler != null)
                {
                    Interlocked.Decrement(ref requestCount);
                    handler.GetResponseAsync(task);
                }
                // Thread.Sleep(10);
            }
        }

在这个方法中我们需要调用GetAvailableHttpRequest来获取IHttpRequest处理对象实例，调用GetTask来获取HttpRequestInfo 请求实例。如果这2个实例都存在我们调用    IHttpRequest.GetResponseAsync(HttpRequestInfo );方法开始处理http请求。

GetAvailableHttpRequest如下：

  private static IHttpRequest GetAvailableHttpRequest()
        {
            lock (Lockobj)
            {
                for (int i = 0; i < Handlers.Count; i++)
                {
                    if (!Handlers[i].IsBusy)
                    {
                        return Handlers[i];
                    }
                }
                if (Handlers.Count <= MaxRequestCount)
                {
                    IHttpRequest handler = (IHttpRequest)Activator.CreateInstance(_httpRequestType);
                    Handlers.Add(handler);
                    return handler;
                }
            }
            return null;
            //return GetAvailableHttpRequest();
        }

在GetAvailableHttpRequest方法中，我们首先在处理对象集合中查找是否有空闲对象，如果有就返回，否则检查当前对象实例个数个数是否达到最大个数，如果没有我们则创建新实例，且加入到集合中，再返回，否者返回null。所以在Process方法中有一个检查，看啊看你返回的IHttpRequest是否为null，请注意这里一定不要用递归来返回有效的IHttpRequest，建议用一个死循环来处理，如果用递归一般不会出现什么问题，但是递归层次嵌套太深就会出现栈溢出错误，我在测试的时候曾经出现过这个问题。GetTask和GetAvailableHttpRequest处理一样。

那么这里的Process方法有在什么地方调用了，在HttpRequestFactory的静态构造函数中调用。

    static HttpRequestFactory()
        {
            MaxRequestCount = 10;
            ThreadPool.QueueUserWorkItem(new WaitCallback(Process));
        }
到这里我们的一个对象池就构造玩了。

二 现在我们来看看RequestHttpWebRequest是如何处理HTTP请求的。它主要使用HttpWebRequest来处理请求。

这里我们主要使用HttpWebRequest的异步方法，因此我们需要构造一个状态对象StateObjectInfo

   class StateObjectInfo : HttpContextInfo
        {
            internal byte[] Buffer { set; get; } //把返回的流写到HttpResponseInfo.ResponseContent 时用到的暂存数组
            internal Stream ReadStream { set; get; }//把返回的流写到HttpResponseInfo.ResponseContent
            internal HttpWebRequest HttpWebRequest { set; get; }
            internal RequestHttpWebRequest RequestHandler { set; get; }//主要便于后面改IsBusy属性。
        }

其GetResponseAsync实现如下：

public void GetResponseAsync(HttpRequestInfo info)
        {
            HttpWebRequest webRequest;
            StateObjectInfo state;
            InitWebRequest(info, out webRequest, out state);
            try
            {
                if (IsHttpPost)
                {
                    webRequest.Method = "POST";
                    webRequest.ContentType = "application/x-www-form-urlencoded";
                    webRequest.BeginGetRequestStream(EndRequest, state);
                }
                else
                {
                    webRequest.BeginGetResponse(EndResponse, state);
                }

            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }

其中InitWebRequest的实现如下：

  private void InitWebRequest(HttpRequestInfo info, out HttpWebRequest webRequest, out StateObjectInfo state)
        {
            IsBusy = true;
            if (info.PostData != null && info.PostData.Length > 0)
            {
                IsHttpPost = true;
            }
            else
            {
                IsHttpPost = false;
            }
            if (info.Url.ToLower().Trim().StartsWith("https"))
            {
                IsHttps = true;
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
            }
            else
            {
                IsHttps = false;
            }
            webRequest = HttpWebRequest.CreateDefault(new Uri(info.Url)) as HttpWebRequest;
            if (IsHttps)
            {
                /*基础连接已经关闭: 发送时发生错误 */
                /*无法从传输连接中读取数据: 远程主机强迫关闭了一个现有的连接*/
                webRequest.KeepAlive = false;
                webRequest.ProtocolVersion = HttpVersion.Version10;
                webRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)";
            }
            webRequest.AllowAutoRedirect = info.AllowAutoRedirect;
            if (info.Headers != null && info.Headers.Count > 0)
            {
                foreach (string key in info.Headers.Keys)
                {
                    webRequest.Headers.Add(key, info.Headers[key]);
                }
            }
            //webRequest.Proxy = WebProxy.GetDefaultProxy();   
            //webRequest.Proxy.Credentials = CredentialCache.DefaultCredentials;     
            //webResponse.Headers.Get("Set-Cookie");   
            state = new StateObjectInfo
            {
                Buffer = new byte[1024 * 1024],
                HttpWebRequest = webRequest,
                RequestHandler = this,
                RequestInfo = info,
                ResponseInfo = new HttpResponseInfo()

            };
        }

关于该类的EndRequest、EndResponse我想就没什么说的了，其中ReadCallBack的实现如下：

   void ReadCallBack(IAsyncResult ar)
        {
            StateObjectInfo state = ar.AsyncState as StateObjectInfo;
            try
            {
                int read = state.ReadStream.EndRead(ar);
                if (read > 0)
                {
                    state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, read);
                    state.ReadStream.BeginRead(state.Buffer, 0, state.Buffer.Length, ReadCallBack, state);
                }
                else
                {
                    state.ReadStream.Close();
                    state.HttpWebRequest.Abort();
                    if (state.RequestInfo.ActionCompleted != null)
                    {
                        state.ResponseInfo.ResponseContent.Seek(0, SeekOrigin.Begin);
                        state.RequestInfo.ActionCompleted(state);
                    }
                    state.Buffer = null;
                    state.RequestHandler.IsBusy = false;
                }
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }

这里还有一个HandException方法需要我们注意：

   private void HandException(Exception ex, StateObjectInfo state)
        {
            if (state.ReadStream != null)
                state.ReadStream.Close();
            if (state.HttpWebRequest != null)
                state.HttpWebRequest.Abort();
            state.Buffer = null;
            if (state.RequestInfo.ActionException != null)
            {
                state.RequestInfo.ActionException(new HttpRequestException(state, ex));
            }
            state.RequestHandler.IsBusy = false;
        }

这里我们在使用HttpWebRequest的时候，在完成使用后一定要关闭请求流。

在我们来看看一个简单的调用把：

  public static void DownLoadFile(string remoteurl, string destinationFilePath, string id)
        {
            try
            {
                if (HasIllegalCharacters(destinationFilePath, false))
                {
                    SetFileCopyed(id, "400", "HasIllegalCharacters");
                    return;
                }
                DirectoryInfo dir = new DirectoryInfo(destinationFilePath);
                FileInfo destinationFile = new FileInfo(destinationFilePath);
                if (!destinationFile.Directory.Exists)
                {
                    destinationFile.Directory.Create();
                }
                HttpRequestInfo request = new HttpRequestInfo(remoteurl);
                request.ActionCompleted = new Action<HttpContextInfo>(x =>
                {
                    if (x.ResponseInfo.StatusCode == HttpStatusCode.OK)
                    {
                        using (Stream wr = File.Open(destinationFilePath, FileMode.OpenOrCreate, FileAccess.Write), sr = x.ResponseInfo.ResponseContent)
                        {                   
                            byte[] data = new byte[1024 * 1024];
                            int readcount = sr.Read(data, 0, data.Length);
                            while (readcount > 0)
                            {
                                wr.Write(data, 0, readcount);
                                readcount = sr.Read(data, 0, data.Length);
                            }
                        }
                        SetFileCopyed(id, "200", string.Empty);
                    }
                    else
                    {
                        SetFileCopyed(id, ((int)x.ResponseInfo.StatusCode).ToString(), x.ResponseInfo.StatusDescription);
                        string message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + remoteurl + " : " + x.ResponseInfo.StatusDescription;
                        LogManager.LogException(message);
                    }
                });
                request.ActionException = new Action<HttpRequestException>(ex =>
                {
                    Regex reg = new Regex(@"d{3}",RegexOptions.Compiled);
                    string message = ex.Message;
                    Match m = reg.Match(message);
                    if (m.Success)
                    {
                        SetFileCopyed(id, m.Value, message);
                    }
                    else
                    {
                        SetFileCopyed(id, "503", message);
                        HttpRequestInfo newRequest = ex.HttpContextInfo.RequestInfo.Clone();
                        request.ActionCompleted = null;
                        request.ActionException = null;
                        HttpRequestFactory.AddRequestTask(newRequest);
                    }
                    message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + ex.HttpContextInfo.RequestInfo.Url + " : " + message;
                    LogManager.LogException(message);
                });
             
                HttpRequestFactory.AddRequestTask(request);
            }
            catch (Exception ex)
            {
                SetFileCopyed(id, "-1", ex.Message);
                string message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + remoteurl + " : " + ex.Message;
                LogManager.LogException(message);
            }
        }

        internal static bool HasIllegalCharacters(string path, bool checkAdditional)
        {
            for (int i = 0; i < path.Length; i++)
            {
                int num2 = path[i];
                if (((num2 == 0x22) || (num2 == 60)) || (((num2 == 0x3e) || (num2 == 0x7c)) || (num2 < 0x20)))
                {
                    return true;
                }
                if (checkAdditional && ((num2 == 0x3f) || (num2 == 0x2a)))
                {
                    return true;
                }
            }
            return false;
        }

对于这个调用的demo我这里就不多说，不过在调用的时候偶尔会出现：

 /*基础连接已经关闭: 发送时发生错误 */
/*无法从传输连接中读取数据: 远程主机强迫关闭了一个现有的连接*/

这样的错误，网上有一些什么改良方法，我测试后都不管用，个人猜测是与网络有关的，即使我用socket来做偶尔也会有一些问题。所以当我们遇到这些网络问题的时候，我们把我们的请求再次加入请求队列中 HttpRequestFactory.AddRequestTask(newRequest);。这一很重要的哦。

HttpWebRequest类对我们做http请求做了很多封装，我们使用也很方便。但是它的性能比我们自己用socket要低很多，同时在一些处理上违背了我们的操作习惯。如我们上面的调用代码：

如果我们http返回状态是403、404...（除200以外）程序没有进入我的else，而是进入我的ActionException方法里面了，这点让我很是不爽。于是萌生了用socket来做http请求的念头。

三  现在我们来看看SocketHttpRequest是如何处理HTTP请求的。它主要使用Socket来处理请求。

SocketHttpRequest和RequestHttpWebRequest一样都是采用对象的异步模式，那么也需要一个状态对象：
        class RequestSockeStateObject : HttpContextInfo
        {
            internal SocketHttpRequest RequestHandler { set; get; }
            internal Socket _socket { set; get; } //普通http请求采用socket
            internal List<byte> HeaderBuffer { set; get; }
            internal byte[] Buffer { set; get; }
            internal int ContentLength { set; get; }//http需要接收的数据长度
            internal int ReceiveLength { set; get; }//http已经接收的数据长度
            internal SslStream SslStream { set; get; }//https请求采用TcpClient，这里需要用到SslStream
        }

  public void GetResponseAsync(HttpRequestInfo info)
        {
            RequestSockeStateObject _state;
            InitRequestSockeStateObject(info, out _state);
            SocketConnection(_state);
        }

这里的InitRequestSockeStateObject和RequestHttpWebRequest的InitWebRequest方法差不多，就不在累赘了。

主要看看SocketConnection方法：

   void SocketConnection(RequestSockeStateObject _state)
        {
            try
            {
                Uri uri = new Uri(_state.RequestInfo.Url);
                IPHostEntry hostEntry = Dns.GetHostEntry(uri.Host);
                if (IsHttps)
                {
                    TcpClient tcpclient = new TcpClient();
                    tcpclient.Connect(hostEntry.AddressList, uri.Port);
                    _state._socket = tcpclient.Client;
                    SslStream sslStream = new SslStream(tcpclient.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);
                    sslStream.AuthenticateAsClient(hostEntry.HostName, new X509CertificateCollection(), SslProtocols.Ssl3 | SslProtocols.Tls, false);
                    _state.SslStream = sslStream;
                    Begin_Write(_state);
                }
                else
                {
                    Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                    client.Connect(hostEntry.AddressList, uri.Port);
                    _state._socket = client;
                    BeginSend(_state);
                }
            }
            catch (Exception ex)
            {
                HandException(ex, _state);
            }
        }

socket连接是需要IP和端口的，这里我们借用 Uri来获取所需端口，但是一台计算机的ip可能有很多个，实际只有一两个可以连接，所以我们这里需要调用 client.Connect(hostEntry.AddressList, uri.Port)方法，传递一个ip集合。如果是https的话，直接用socket我没有搞定，最后用SslStream 搞定，不知道大家有没有其他方法。

其中Begin_Write、End_Write、Complete_Read方法是sslStream异步中所必需的方法，BeginSend、Send_Completed、Receive_Completed、RepeatReceive是socket异步中所需方法。其中Complete_Read和Receive_Completed方法相似。

  protected virtual void Complete_Read(IAsyncResult ar)
        {
            RequestSockeStateObject state = ar.AsyncState as RequestSockeStateObject;
            try
            {
                int byteCount = state.SslStream.EndRead(ar);
                if (state.ResponseInfo.Headers.Count < 1)
                {
                    SetResponseHeaders(state, byteCount);
                    if ((state.ReceiveLength == state.ContentLength && state.ContentLength > 0))
                    {
                        EndReceive(state);
                    }
                    else
                    {
                        state.SslStream.BeginRead(state.Buffer, 0, state.Buffer.Length, Complete_Read, state);
                    }
                }
                else
                {
                    if (byteCount > 0 && byteCount==state.Buffer.Length)
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, byteCount);
                        state.SslStream.BeginRead(state.Buffer, 0, state.Buffer.Length, Complete_Read, state);
                    }
                    else
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, byteCount);
                        EndReceive(state);
                    }
                }

            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }

 如果是第一次接收数据流，我们必须把数据流中http头部信息取出来，再把头部信息以外的数据流写到HttpResponseInfo.ResponseContent中，如果我们已经接收的数据等于我们需要接收的数据，就表示我们已经接收完毕了。如果没有就继续接收数据。在第二次及以后所接收数据过程中，我们需要判断接收数据长度是否小于接收数组的长度，如果小于就表示接收完毕了，否则继续接收。这里的EndReceive方法如下：

 void EndReceive(RequestSockeStateObject state)
        {
            /*
             * if (state.RequestInfo.AllowAutoRedirect &&
                                   (state.ResponseInfo.StatusCode == HttpStatusCode.Found || state.ResponseInfo.StatusCode == HttpStatusCode.MovedPermanently))
                {
                    string location = state.ResponseInfo.Headers["Location"];
                    state.RequestInfo.Url = location;
                    state.RequestInfo.Headers = state.ResponseInfo.Headers;
                    state.RequestInfo.Headers.Remove("Location");
                    state.RequestInfo.Headers.Add("Referer", location);
                    Begin_Write(state);
                }
             */
            if (IsHttps)
            {
                state.SslStream.Close();
                state.SslStream = null;
            }
            else
            {
                state._socket.Shutdown(SocketShutdown.Both);
                state._socket.Close();
                state._socket = null;
            }
            if (state.RequestInfo.ActionCompleted != null)
            {
                state.ResponseInfo.ResponseContent.Seek(0, SeekOrigin.Begin);
                state.RequestInfo.ActionCompleted(state);
            }
            state.RequestHandler.IsBusy = false;

        }

EndReceive方法主要是关闭socket或则SslStream数据流，然后调用ActionCompleted方法。在这里 state.ResponseInfo.ResponseContent.Seek(0, SeekOrigin.Begin);这个方法非常重要，不然在外面的调用方法就必须调用Stream.Seek(0, SeekOrigin.Begin)来吧数据流定位开始位置。

 在SocketHttpRequest这个类中，我们是如何来获取发送的http请求信息以及如何解析http返回的header信息了？

首先来看一个GetRequestData方法，它主要是通过RequestInfo实例来获取请求信息：

namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Net;

    [Serializable]
    public class HttpRequestInfo
    {
        public HttpRequestInfo(string url)
        {
            Url = url;
            Headers = new WebHeaderCollection();
            ExternalData = new Dictionary<string, string>();
        }
        public string Url { set; get; }
        public byte[] PostData { set; get; }
        public WebHeaderCollection Headers { set; get; }
        public bool AllowAutoRedirect { set; get; }
        public Dictionary<string, string> ExternalData { set; get; }
        public Action<HttpContextInfo> ActionCompleted { set; get; }
        public Action<HttpRequestException> ActionException { set; get; }

        public HttpRequestInfo Clone()
        {
            HttpRequestInfo newobj = new HttpRequestInfo(this.Url)
            {
                AllowAutoRedirect = this.AllowAutoRedirect,
                ActionCompleted = this.ActionCompleted,
                ActionException = this.ActionException
            };
            if (PostData != null && PostData.Length > 0)
            {
                newobj.PostData = new byte[this.PostData.Length];
                Array.Copy(this.PostData, 0, newobj.PostData, 0, this.PostData.Length);
            }
            if (Headers.Count > 0)
            {
                foreach (string key in Headers.Keys)
                {
                    newobj.Headers.Add(key, Headers[key]);
                }
            }
            if (ExternalData.Count > 0)
            {
                foreach (string key in ExternalData.Keys)
                {
                    newobj.ExternalData.Add(key, ExternalData[key]);
                }
            }
            return newobj;
        }
    }
    public class HttpRequestException : Exception
    {
        public HttpRequestException(HttpContextInfo context, Exception ex)
            : base(ex.Message, ex)
        {
            HttpContextInfo = context;
        }
        public HttpContextInfo HttpContextInfo { set; get; }
    }
}
namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.IO;
    using System.Net;

    [Serializable]
    public class HttpResponseInfo
    {
        public HttpResponseInfo()
        {
            ResponseContent = new MemoryStream();
            Headers = new WebHeaderCollection();
        }
        public Stream ResponseContent { set; get; }
        HttpStatusCode _statusCode;
        public HttpStatusCode StatusCode
        {
            set
            {
                _statusCode = value;
                StatusDescription = System.Web.HttpWorkerRequest.GetStatusDescription((int)_statusCode);
            }
            get
            {
                return _statusCode;
            }
        }
        public string StatusDescription { set; get; }
        public WebHeaderCollection Headers { set; get; }
        public string GetString(Encoding coding)
        {
            StringBuilder str = new StringBuilder();
            Stream sr = ResponseContent;
            byte[] data = new byte[1024 * 100];
            int readcount = sr.Read(data, 0, data.Length);
            while (readcount > 0)
            {
                str.Append(coding.GetString(data, 0, readcount));
                readcount = sr.Read(data, 0, data.Length);
            }
            ResponseContent.Seek(0, SeekOrigin.Begin);
            return str.ToString();
        }
    }

    public class HttpContextInfo
    {
        public HttpResponseInfo ResponseInfo { set; get; }
        public HttpRequestInfo RequestInfo { set; get; }
    }
    public interface IHttpRequest
    {
        void GetResponseAsync(HttpRequestInfo request);
        bool IsBusy { set; get; }
    }
}
namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.IO;
    using System.Data;
    using System.Data.OleDb;
    using System.Net;
    using System.Xml;
    using System.Net.Security;
    using System.Security.Cryptography.X509Certificates;

    public class RequestHttpWebRequest : IHttpRequest
    {
        class StateObjectInfo : HttpContextInfo
        {
            internal byte[] Buffer { set; get; }
            internal Stream ReadStream { set; get; }
            internal HttpWebRequest HttpWebRequest { set; get; }
            internal RequestHttpWebRequest RequestHandler { set; get; }
        }

        private bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            //直接确认，否则打不开     
            return true;
        }
        public void GetResponseAsync(HttpRequestInfo info)
        {
            HttpWebRequest webRequest;
            StateObjectInfo state;
            InitWebRequest(info, out webRequest, out state);
            try
            {
                if (IsHttpPost)
                {
                    webRequest.Method = "POST";
                    webRequest.ContentType = "application/x-www-form-urlencoded";
                    webRequest.BeginGetRequestStream(EndRequest, state);
                }
                else
                {
                    webRequest.BeginGetResponse(EndResponse, state);
                }
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        void EndRequest(IAsyncResult ar)
        {
            StateObjectInfo state = ar.AsyncState as StateObjectInfo;
            try
            {
                HttpWebRequest webRequest = state.HttpWebRequest as HttpWebRequest;
                using (Stream stream = webRequest.EndGetRequestStream(ar))
                {
                    byte[] data = state.RequestInfo.PostData;
                    stream.Write(data, 0, data.Length);
                }
                webRequest.BeginGetResponse(EndResponse, state);
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        void EndResponse(IAsyncResult ar)
        {
            StateObjectInfo state = ar.AsyncState as StateObjectInfo;
            try
            {
                HttpWebResponse webResponse = state.HttpWebRequest.EndGetResponse(ar) as HttpWebResponse;
                state.ResponseInfo.StatusCode = webResponse.StatusCode;
                state.ResponseInfo.StatusDescription = webResponse.StatusDescription;
                foreach (string key in webResponse.Headers.AllKeys)
                {
                    state.ResponseInfo.Headers.Add(key, webResponse.Headers[key]);
                }
                state.ReadStream = webResponse.GetResponseStream();
                state.ReadStream.BeginRead(state.Buffer, 0, state.Buffer.Length, ReadCallBack, state);
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        void ReadCallBack(IAsyncResult ar)
        {
            StateObjectInfo state = ar.AsyncState as StateObjectInfo;
            try
            {
                int read = state.ReadStream.EndRead(ar);
                if (read > 0)
                {
                    state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, read);
                    state.ReadStream.BeginRead(state.Buffer, 0, state.Buffer.Length, ReadCallBack, state);
                }
                else
                {
                    state.ReadStream.Close();
                    state.HttpWebRequest.Abort();
                    if (state.RequestInfo.ActionCompleted != null)
                    {
                        state.ResponseInfo.ResponseContent.Seek(0, SeekOrigin.Begin);
                        state.RequestInfo.ActionCompleted(state);
                    }
                    state.Buffer = null;
                    state.RequestHandler.IsBusy = false;
                }
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        private void InitWebRequest(HttpRequestInfo info, out HttpWebRequest webRequest, out StateObjectInfo state)
        {
            IsBusy = true;
            if (info.PostData != null && info.PostData.Length > 0)
            {
                IsHttpPost = true;
            }
            else
            {
                IsHttpPost = false;
            }
            if (info.Url.ToLower().Trim().StartsWith("https"))
            {
                IsHttps = true;
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
            }
            else
            {
                IsHttps = false;
            }
            webRequest = HttpWebRequest.CreateDefault(new Uri(info.Url)) as HttpWebRequest;
            if (IsHttps)
            {
                /*基础连接已经关闭: 发送时发生错误 */
                /*无法从传输连接中读取数据: 远程主机强迫关闭了一个现有的连接*/
                webRequest.KeepAlive = false;
                webRequest.ProtocolVersion = HttpVersion.Version10;
                webRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)";
            }
            webRequest.AllowAutoRedirect = info.AllowAutoRedirect;
            if (info.Headers != null && info.Headers.Count > 0)
            {
                foreach (string key in info.Headers.Keys)
                {
                    webRequest.Headers.Add(key, info.Headers[key]);
                }
            }
            //webRequest.Proxy = WebProxy.GetDefaultProxy();   
            //webRequest.Proxy.Credentials = CredentialCache.DefaultCredentials;     
            //webResponse.Headers.Get("Set-Cookie");   
            state = new StateObjectInfo
            {
                Buffer = new byte[1024 * 100],
                HttpWebRequest = webRequest,
                RequestHandler = this,
                RequestInfo = info,
                ResponseInfo = new HttpResponseInfo()

            };
        }
        private bool IsHttpPost { set; get; }
        private bool IsHttps { set; get; }
        public bool IsBusy { set; get; }
        private void HandException(Exception ex, StateObjectInfo state)
        {
            if (state.ReadStream != null)
                state.ReadStream.Close();
            if (state.HttpWebRequest != null)
                state.HttpWebRequest.Abort();
            state.Buffer = null;
            if (state.RequestInfo.ActionException != null)
            {
                state.RequestInfo.ActionException(new HttpRequestException(state, ex));
            }
            state.RequestHandler.IsBusy = false;
        }
    }
}

namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Threading;
    using System.Net;
    public class HttpRequestFactory
    {
        static HttpRequestFactory()
        {
            MaxRequestCount = 10;
            ThreadPool.QueueUserWorkItem(new WaitCallback(Process));
        }

        static readonly object Lockobj = new object();
        static long requestCount = 0;
        static Queue<HttpRequestInfo> requestTask = new Queue<HttpRequestInfo>();
        static List<IHttpRequest> Handlers = new List<IHttpRequest>();

        public static void AddRequestTask(HttpRequestInfo info)
        {
            if (!string.IsNullOrEmpty(info.Url))
            {
                lock (Lockobj)
                {
                    requestTask.Enqueue(info);
                    Interlocked.Increment(ref requestCount);
                }
            }
        }

        private static IHttpRequest GetAvailableHttpRequest()
        {
            lock (Lockobj)
            {
                for (int i = 0; i < Handlers.Count; i++)
                {
                    if (!Handlers[i].IsBusy)
                    {
                        return Handlers[i];
                    }
                }
                if (Handlers.Count <= MaxRequestCount)
                {
                    IHttpRequest handler = (IHttpRequest)Activator.CreateInstance(_httpRequestType);
                    Handlers.Add(handler);
                    return handler;
                }
            }
            return null;
            //return GetAvailableHttpRequest();
        }

        private static HttpRequestInfo GetTask()
        {
            HttpRequestInfo task = null;
            lock (Lockobj)
            {
                if (requestTask.Count > 0)
                {
                    task = requestTask.Dequeue();
                    return task;
                }
            }
            return task;
        }

        private static void Process(object obj)
        {
            while (true)
            {
                IHttpRequest handler = GetAvailableHttpRequest();
                while (handler == null)
                {
                    Thread.Sleep(500);
                    handler = GetAvailableHttpRequest();
                }
                HttpRequestInfo task = GetTask();
                while (task == null)
                {
                    Thread.Sleep(500);
                    task = GetTask();
                }
                if (task != null && handler != null)
                {
                    handler.GetResponseAsync(task);
                    Interlocked.Decrement(ref requestCount);
                    Thread.Sleep(50);
                }
            }

        }
        public static long TaskCount
        {
            get
            {
                return Interlocked.Read(ref requestCount);
            }
        }
        static int _maxRequestCount = 2;
        public static int MaxRequestCount
        {
            set
            {
                _maxRequestCount = value;
                ServicePointManager.DefaultConnectionLimit = _maxRequestCount * 2;
            }
            get
            {
                return _maxRequestCount;
            }
        }

        static Type _httpRequestType = typeof(RequestHttpWebRequest);
        public static void SetHttpRequestType(Type type)
        {
            if (type.IsClass && typeof(IHttpRequest).IsAssignableFrom(type))
            {
                _httpRequestType = type;
            }
        }
    }
}

namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.Text;
    using System.Threading;
    using System.Reflection;
    using System.IO;
    public class LogManager
    {
        static object lockobj = new object();
        static Queue<string> Messages = new Queue<string>();
        static long messageCount = 0;
        static LogManager()
        {
            ThreadPool.QueueUserWorkItem(new WaitCallback(Work));
        }
        public static void LogException(Exception ex)
        {
            Type type = ex.GetType();
            StringBuilder sb = new StringBuilder();
            sb.AppendLine(type.ToString() + "--------" + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
            PropertyInfo[] properties = type.GetProperties();
            foreach (PropertyInfo p in properties)
            {
                if (p.PropertyType == typeof(string))
                {
                    object msg = p.GetValue(ex, null);
                    if (msg != null)
                        sb.AppendLine(p.Name + ":" + msg.ToString());
                }
            }
            lock (lockobj)
            {
                LogException(sb.ToString());
            }
        }
        public static void LogException(string msg)
        {
            lock (lockobj)
            {
                Messages.Enqueue(msg);
                Interlocked.Increment(ref messageCount);
            }

        }
        static void Work(object obj)
        {
            if (!File.Exists(ExceptionLogFilePath))
            {
                FileStream fs = File.Create(ExceptionLogFilePath);
                fs.Close();
            }

            while (true)
            {
                if (MessageCount > 0)
                {
                    string msg = string.Empty;
                    lock (lockobj)
                    {
                        msg = Messages.Dequeue();
                        Interlocked.Decrement(ref messageCount);

                        if (!string.IsNullOrEmpty(msg))
                        {
                            using (StreamWriter sw = new StreamWriter(ExceptionLogFilePath, true, Encoding.UTF8))
                            {
                                sw.Write(msg);
                                sw.WriteLine();
                                sw.Flush();
                            }
                        }
                    }

                }//end if
                Thread.Sleep(500);
            }

        }//end
         static long MessageCount
        {
            get
            {
                return Interlocked.Read(ref messageCount);
            }
        }
        public static string ExceptionLogFilePath { set; get; }
    }
}

SocketHttpRequest代码：

namespace HttpRequest
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Net;
    using System.Net.Security;
    using System.Net.Sockets;
    using System.Security.Authentication;
    using System.Security.Cryptography.X509Certificates;
    using System.Text;
    using System.Text.RegularExpressions;

    public class SocketHttpRequest : IHttpRequest
    {
        class RequestSockeStateObject : HttpContextInfo
        {
            internal SocketHttpRequest RequestHandler { set; get; }
            internal Socket _socket { set; get; }
            internal List<byte> HeaderBuffer { set; get; }
            internal byte[] Buffer { set; get; }
            internal int ContentLength { set; get; }
            internal int ReceiveLength { set; get; }
            internal SslStream SslStream { set; get; }
        }
        public void GetResponseAsync(HttpRequestInfo info)
        {
            RequestSockeStateObject _state;
            InitRequestSockeStateObject(info, out _state);
            SocketConnection(_state);
        }
        void SocketConnection(RequestSockeStateObject _state)
        {
            try
            {
                Uri uri = new Uri(_state.RequestInfo.Url);
                IPHostEntry hostEntry = Dns.GetHostEntry(uri.Host);
                if (IsHttps)
                {
                    TcpClient tcpclient = new TcpClient();
                    tcpclient.Connect(hostEntry.AddressList, uri.Port);
                    _state._socket = tcpclient.Client;
                    SslStream sslStream = new SslStream(tcpclient.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);
                    sslStream.AuthenticateAsClient(hostEntry.HostName, new X509CertificateCollection(), SslProtocols.Ssl3 | SslProtocols.Tls, false);
                    _state.SslStream = sslStream;
                    Begin_Write(_state);
                }
                else
                {
                    Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                    client.Connect(hostEntry.AddressList, uri.Port);
                    _state._socket = client;
                    BeginSend(_state);
                }
            }
            catch (Exception ex)
            {
                HandException(ex, _state);
            }
        }

        #region SSL Https
        void Begin_Write(RequestSockeStateObject state)
        {
            try
            {
                byte[] requestData = GetRequestData(state);
                state.SslStream.BeginWrite(requestData, 0, requestData.Length, End_Write, state);
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }

        }
        protected virtual void End_Write(IAsyncResult ar)
        {
            RequestSockeStateObject state = ar.AsyncState as RequestSockeStateObject;
            try
            {
                state.SslStream.EndWrite(ar);
                state.SslStream.Flush();
                state.SslStream.BeginRead(state.Buffer, 0, state.Buffer.Length, Complete_Read, state);
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        protected virtual void Complete_Read(IAsyncResult ar)
        {
            RequestSockeStateObject state = ar.AsyncState as RequestSockeStateObject;
            try
            {
                int byteCount = state.SslStream.EndRead(ar);
                if (state.ResponseInfo.Headers.Count < 1)
                {
                    SetResponseHeaders(state, byteCount);
                    if ((state.ReceiveLength == state.ContentLength && state.ContentLength > 0))
                    {
                        EndReceive(state);
                    }
                    else
                    {
                        state.SslStream.BeginRead(state.Buffer, 0, state.Buffer.Length, Complete_Read, state);
                    }
                }
                else
                {
                    if (byteCount > 0 && byteCount == state.Buffer.Length)
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, byteCount);
                        state.SslStream.BeginRead(state.Buffer, 0, state.Buffer.Length, Complete_Read, state);
                    }
                    else
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, byteCount);
                        EndReceive(state);
                    }
                }

            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        #endregion

        #region Http
        void BeginSend(RequestSockeStateObject state)
        {
            try
            {
                byte[] byteData = GetRequestData(state);
                SocketAsyncEventArgs arg = new SocketAsyncEventArgs
                {
                    UserToken = state,
                    RemoteEndPoint = state._socket.RemoteEndPoint
                };
                arg.SetBuffer(byteData, 0, byteData.Length);
                arg.Completed += new EventHandler<SocketAsyncEventArgs>(Send_Completed);
                bool send = state._socket.SendAsync(arg);
                if (!send)
                {
                    HandException(new SocketException((int)SocketError.NoData), state);
                }
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }

        protected virtual void Send_Completed(object sender, SocketAsyncEventArgs e)
        {
            RequestSockeStateObject state = e.UserToken as RequestSockeStateObject;
            try
            {
                if (e.SocketError == SocketError.Success)
                {
                    SocketAsyncEventArgs arg = new SocketAsyncEventArgs
                    {
                        UserToken = state,
                        RemoteEndPoint = state._socket.RemoteEndPoint,
                    };
                    arg.Completed += new EventHandler<SocketAsyncEventArgs>(Receive_Completed);
                    arg.SetBuffer(state.Buffer, 0, state.Buffer.Length);
                    bool receive = state._socket.ReceiveAsync(arg);
                    if (!receive)
                    {
                        HandException(new SocketException((int)SocketError.NoData), state);
                    }
                }
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }

        protected virtual void Receive_Completed(object sender, SocketAsyncEventArgs e)
        {
            RequestSockeStateObject state = e.UserToken as RequestSockeStateObject;
            if (e.SocketError == SocketError.Success)
            {
                if (state.ResponseInfo.Headers.Count < 1)
                {
                    if (e.BytesTransferred > 0) {
                        SetResponseHeaders(state, e.BytesTransferred);
                    }                  
                    if ((state.ReceiveLength == state.ContentLength && state.ContentLength > 0) || !state._socket.Connected)
                    {
                        EndReceive(state);
                    }
                    else
                    {
                        RepeatReceive(state);
                    }
                }
                else
                {
                    if ((e.BytesTransferred > 0 && e.BytesTransferred == state.Buffer.Length) || state._socket.Connected)
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, e.BytesTransferred);
                        RepeatReceive(state);
                    }
                    else
                    {
                        state.ResponseInfo.ResponseContent.Write(state.Buffer, 0, e.BytesTransferred);
                        EndReceive(state);
                    }
                }
            }
            else
            {
                HandException(new SocketException((int)e.SocketError), state);
            }
        }
        //end

        void RepeatReceive(RequestSockeStateObject state)
        {
            SocketAsyncEventArgs arg = new SocketAsyncEventArgs
            {
                UserToken = state,
                RemoteEndPoint = state._socket.RemoteEndPoint,
            };

            arg.Completed += new EventHandler<SocketAsyncEventArgs>(Receive_Completed);
            arg.SetBuffer(state.Buffer, 0, state.Buffer.Length);
            bool receive = state._socket.ReceiveAsync(arg);
            if (!receive)
            {
                HandException(new SocketException((int)SocketError.SocketError), state);
            }
        }
        #endregion

        void EndReceive(RequestSockeStateObject state)
        {
            /*
             * if (state.RequestInfo.AllowAutoRedirect &&
                                   (state.ResponseInfo.StatusCode == HttpStatusCode.Found || state.ResponseInfo.StatusCode == HttpStatusCode.MovedPermanently))
                {
                    string location = state.ResponseInfo.Headers["Location"];
                    state.RequestInfo.Url = location;
                    state.RequestInfo.Headers = state.ResponseInfo.Headers;
                    state.RequestInfo.Headers.Remove("Location");
                    state.RequestInfo.Headers.Add("Referer", location);
                    Begin_Write(state);
                }
             */
            if (IsHttps)
            {
                state.SslStream.Close();
                state.SslStream = null;
            }
            else
            {
                if (state._socket.Connected)
                    state._socket.Shutdown(SocketShutdown.Both);
                state._socket.Close();
                state._socket = null;
            }
            if (state.RequestInfo.ActionCompleted != null)
            {
                state.ResponseInfo.ResponseContent.Seek(0, SeekOrigin.Begin);
                state.RequestInfo.ActionCompleted(state);
            }
            state.RequestHandler.IsBusy = false;

        }

        #region Set Response Header
        /// <summary>
        /// 判断读取的信息中是否包含返回头的结束符，如果有则取出返回头的信息
        /// </summary>
        /// <param name="state">状态信息</param>
        /// <param name="bytesRead">读取的字节数</param>
        void SetResponseHeaders(RequestSockeStateObject state, int bytesRead)
        {
            try
            {
                byte[] tempArray = new byte[bytesRead];
                Array.Copy(state.Buffer, 0, tempArray, 0, bytesRead);
                state.HeaderBuffer.AddRange(tempArray);
                tempArray = state.HeaderBuffer.ToArray();
                string headerSpilt = "

";
                byte[] headerbyte = Encoding.ASCII.GetBytes(headerSpilt);
                int contentindex = DestTag(tempArray, headerbyte, 0, tempArray.Length);
                if (contentindex > 0)
                {
                    string headerStr = Encoding.ASCII.GetString(tempArray, 0, contentindex);
                    int startIndex = contentindex + headerbyte.Length;
                    SetResponseHeaders(headerStr, state);
                    state.ReceiveLength = tempArray.Length - startIndex;
                    state.ResponseInfo.ResponseContent.Write(tempArray, startIndex, tempArray.Length - startIndex);
                    state.HeaderBuffer.Clear();
                }

            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        /// <summary>
        /// 设置ResponseInfo的返回头，并且检查返回头是否含有Keep-Alive和Content-Length
        /// </summary>
        /// <param name="headerStr">字符串形式的返回头</param>
        /// <param name="state">整个异步处理过程中的对象</param>
        void SetResponseHeaders(string headerStr, RequestSockeStateObject state)
        {
            try
            {
                string[] headers = headerStr.Split(new string[] { "
" }, StringSplitOptions.RemoveEmptyEntries);
                string statline = headers[0];
                state.ResponseInfo.StatusCode = GetStatusCode(statline);
                for (int i = 1; i < headers.Length; i++)
                {
                    int index = headers[i].IndexOf(":");
                    if (index > 1)
                    {
                        string key = headers[i].Substring(0, index);
                        string value = headers[i].Substring(index + 1);
                        state.ResponseInfo.Headers.Add(key.Trim(), value.Trim());
                    }
                }
                string contentLength = state.ResponseInfo.Headers["Content-Length"];
                int length = 0;
                if (int.TryParse(contentLength, out length))
                {
                    state.ContentLength = length;
                }              
                state.ReceiveLength = 0;
            }
            catch (Exception ex)
            {
                HandException(ex, state);
            }
        }
        HttpStatusCode GetStatusCode(string text)
        {
            Regex reg = new Regex(@"d{3}");
            Match m = reg.Match(text);
            string code = m.Value;
            HttpStatusCode statu = (HttpStatusCode)Enum.Parse(typeof(HttpStatusCode), code, true);
            return statu;
        }

        /// <summary>
        /// 在指定的数组中检索短数组
        /// </summary>
        /// <param name="buffer">要检索的大数组</param>
        /// <param name="tag">待检索的小字数组</param>
        /// <param name="startIndex">检完索的启始索引</param>
        /// <param name="maxLength">大数组的有效长度</param>
        /// <returns>如检索到，则返回启始索引，否则返回-1</returns>
        protected int DestTag(byte[] buffer, byte[] tag, int startIndex, int maxLength)
        {
            bool temp = true;
            int endIndex = maxLength - tag.Length;
            while (startIndex < maxLength - tag.Length)
            {
                temp = true;
                int pos = Array.IndexOf(buffer, tag[0], startIndex, endIndex - startIndex);
                if (pos < 0)
                {
                    return -1;
                }
                for (int j = 0; j < tag.Length; j++) //匹配所有字节
                {
                    if (buffer[pos + j] != tag[j])
                    {
                        if (pos > startIndex)
                            startIndex = pos;
                        else
                            startIndex++;
                        temp = false;
                        break;
                    }
                }
                if (temp == true)
                {
                    return pos;
                }

            }
            return -1;
        }

        #endregion


        /// <summary>
        /// 根据指定的uri获取请求头
        /// </summary>
        /// <param name="uri">请求的uri</param>
        /// <returns>以字符串的形式返回请求头</returns>
        byte[] GetRequestData(RequestSockeStateObject _state)
        {
            StringBuilder bufRequest = new StringBuilder();

            Uri uri = new Uri(_state.RequestInfo.Url);
            if (!IsHttpPost)
            {
                bufRequest.Append("GET ").Append(uri.OriginalString).AppendLine(" HTTP/1.1");
            }
            else
            {
                bufRequest.Append("POST ").Append(uri.OriginalString).AppendLine(" HTTP/1.1");
                string contentLengthkey = "Content-Length";
                string contentTypekey = "Content-Type";
                List<string> headerKeys = new List<string>(_state.RequestInfo.Headers.AllKeys);
                if (headerKeys.Contains(contentLengthkey))
                {
                    _state.RequestInfo.Headers.Remove(contentLengthkey);
                }
                if (headerKeys.Contains(contentTypekey))
                {
                    _state.RequestInfo.Headers.Remove(contentTypekey);
                }
                _state.RequestInfo.Headers.Add(contentTypekey, "application/x-www-form-urlencoded");
                _state.RequestInfo.Headers.Add(contentLengthkey, _state.RequestInfo.PostData.Length.ToString());
            }
            _state.RequestInfo.Headers.Add("Host", uri.Host);
            _state.RequestInfo.Headers.Add("Connection", "keep-alive");
            if (_state.RequestInfo.Headers.Count > 0)
            {
                bufRequest.Append(_state.RequestInfo.Headers.ToString());
            }
            byte[] byteData = Encoding.ASCII.GetBytes(bufRequest.ToString());

            if (!IsHttpPost)
            {
                return byteData;
            }
            else
            {
                byte[] sendData = new byte[byteData.Length + _state.RequestInfo.PostData.Length];
                Array.Copy(byteData, 0, sendData, 0, byteData.Length);
                Array.Copy(_state.RequestInfo.PostData, 0, sendData, byteData.Length, _state.RequestInfo.PostData.Length);
                return sendData;
            }
        }
        /// <summary>
        /// 初始化State以及ResponseInfo
        /// </summary>
        /// <param name="info">请求对象</param>
        void InitRequestSockeStateObject(HttpRequestInfo info, out RequestSockeStateObject _state)
        {
            this.IsBusy = true;
            _state = new RequestSockeStateObject()
            {
                RequestHandler = this,
                Buffer = new byte[1024 * 1024],
                HeaderBuffer = new List<byte>(),
                RequestInfo = info,
                ResponseInfo = new HttpResponseInfo()
            };
            if (info.PostData == null || info.PostData.Length < 1)
            {
                IsHttpPost = false;
            }
            else
            {
                IsHttpPost = true;
            }
            if (info.Url.ToLower().Trim().StartsWith("https"))
            {
                IsHttps = true;
            }
            else
            {
                IsHttps = false;
            }
        }

        void HandException(Exception ex, RequestSockeStateObject state)
        {
            if (IsHttps)
            {
                if (state.SslStream != null)
                    state.SslStream.Close();
                else if (state._socket != null)
                {
                    state._socket.Shutdown(SocketShutdown.Both);
                    state._socket.Close();
                }
            }
            else
            {
                state._socket.Shutdown(SocketShutdown.Both);
                state._socket.Close();
            }
            if (state.RequestInfo.ActionException != null)
            {
                state.RequestInfo.ActionException(new HttpRequestException(state, ex));
            }
            state.RequestHandler.IsBusy = false;
        }

        static bool ValidateServerCertificate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
            /*
            if (sslPolicyErrors == SslPolicyErrors.None)
                return true;
            Console.WriteLine("Certificate error: {0}", sslPolicyErrors);
            return false;
            */
            return true;
        }

        bool IsHttps { set; get; }
        bool IsHttpPost { set; get; }
        public bool IsBusy
        {
            set;
            get;
        }
    }
}

 调用代码：

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.OleDb;
using System.Data.SqlClient;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Reflection;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;

namespace HttpRequest
{
    class Program
    {
        static void Main(string[] args)
        {
            LogManager.ExceptionLogFilePath = ConfigurationManager.AppSettings["ExceptionLogFilePath"].Trim();
            ConnectionString = ConfigurationManager.AppSettings["ConnectionString"].Trim();
            string remoteHostUrl = ConfigurationManager.AppSettings["remoteHostUrl"].Trim();
            string destinationBasePath = ConfigurationManager.AppSettings["destinationBasePath"].Trim();
            HttpRequestFactory.MaxRequestCount = Convert.ToInt32(ConfigurationManager.AppSettings["MaxRequestCount"]);
            try
            {
                DateTime startTime = DateTime.Now;
                Console.WriteLine("Start Time:" + startTime.ToLongTimeString());
                AsyncDownLoadFiles(remoteHostUrl, destinationBasePath, null, true);
                DateTime endtime = DateTime.Now;
                Console.WriteLine("End Time:" + endtime.ToLongTimeString());
                TimeSpan tm = endtime - startTime;
                Console.WriteLine(tm.Hours.ToString() + " Hours " + tm.Minutes.ToString() + " Minutes " + tm.Seconds.ToString() + " Seconds");
            }

            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadLine();
        }

        public static void AsyncDownLoadFiles(string remoteHostUrl, string destinationBasePath, List<string> tables, bool download)
        {
            try
            {
                List<string> archiveTables = tables;
                if (archiveTables == null || archiveTables.Count < 1)
                {
                    archiveTables = GetArchiveTables();
                }
                foreach (string tablename in archiveTables)
                {
                    string sql = "SELECT  ID,file_name_path FROM  dbo.Archive_Files WHERE TableName ='" + tablename + "' AND Copyed=0  ORDER BY ID ASC";
                    DataTable dt = GetData(sql);
                    foreach (DataRow row in dt.Rows)
                    {
                        string id = row["ID"].ToString();
                        string file_name_path = row["file_name_path"].ToString();
                        file_name_path = file_name_path.Substring(2);
                        if (download)
                        {
                            AsyncDownLoadFile(remoteHostUrl + file_name_path, destinationBasePath + file_name_path, id);
                        }
                        else
                        {
                            CheckFileExists(destinationBasePath + file_name_path, id);
                        }
                    }

                    while (download)
                    {
                        if (HttpRequestFactory.TaskCount < HttpRequestFactory.MaxRequestCount)
                        {
                            break;
                        }
                        Thread.Sleep(10000);
                    }
                }//end foreach
                while (download)
                {
                    if (HttpRequestFactory.TaskCount < 1)
                    {
                        break;
                    }
                    Thread.Sleep(10000);
                }
                bool finishedDownLoad = HasFinishedDownLoad();
                int times = 0;
                while (!finishedDownLoad && times < HttpRequestFactory.TaskCount)
                {
                    Thread.Sleep(10000);
                    finishedDownLoad = HasFinishedDownLoad();
                    times++;
                }
            }
            catch (Exception ex)
            {
                string message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + ex.Message;
                LogManager.LogException(message);
            }
        }

        public static void AsyncDownLoadFile(string remoteurl, string destinationFilePath, string id)
        {
            try
            {
                if (HasIllegalCharacters(destinationFilePath, true))
                {
                    SetFileCopyed(id, "400", "HasIllegalCharacters");
                    return;
                }
                DirectoryInfo dir = new DirectoryInfo(destinationFilePath);
                FileInfo destinationFile = new FileInfo(destinationFilePath);
                if (!destinationFile.Directory.Exists)
                {
                    destinationFile.Directory.Create();
                }
                HttpRequestInfo request = new HttpRequestInfo(remoteurl);
                request.ActionCompleted = new Action<HttpContextInfo>(x =>
                {
                    try
                    {

                        if (x.ResponseInfo.StatusCode == HttpStatusCode.OK)
                        {
                            using (Stream wr = File.Open(destinationFilePath, FileMode.OpenOrCreate, FileAccess.Write), sr = x.ResponseInfo.ResponseContent)
                            {
                                byte[] data = new byte[1024 * 100];
                                int readcount = sr.Read(data, 0, data.Length);
                                while (readcount > 0)
                                {
                                    wr.Write(data, 0, readcount);
                                    readcount = sr.Read(data, 0, data.Length);
                                }
                            }
                            SetFileCopyed(id, "200", string.Empty);
                        }
                        else
                        {
                            SetFileCopyed(id, ((int)x.ResponseInfo.StatusCode).ToString(), x.ResponseInfo.StatusDescription);
                        }
                    }
                    catch (Exception ea)
                    {
                        SetFileCopyed(id, "-1", ea.Message);
                    }
                });
                request.ActionException = new Action<HttpRequestException>(ex =>
                {
                    try
                    {
                        Regex reg = new Regex(@"d{3}", RegexOptions.Compiled);
                        string message = ex.Message;
                        Match m = reg.Match(message);
                        if (m.Success)
                        {
                            SetFileCopyed(id, m.Value, message);
                        }
                        else
                        {
                            SetFileCopyed(id, "503", message);
                            HttpRequestInfo newRequest = ex.HttpContextInfo.RequestInfo.Clone();
                            request.ActionCompleted = null;
                            request.ActionException = null;
                            HttpRequestFactory.AddRequestTask(newRequest);
                        }
                    }
                    catch (Exception ea)
                    {
                        SetFileCopyed(id, "-1", ea.Message);
                    }
                });

                HttpRequestFactory.AddRequestTask(request);
            }
            catch (Exception ex)
            {
                SetFileCopyed(id, "-1", ex.Message);
            }
        }

        private static void CheckFileExists(string destinationFilePath, string id)
        {
            try
            {
                if (HasIllegalCharacters(destinationFilePath, true))
                {
                    SetFileCopyed(id, "400", "HasIllegalCharacters");
                    return;
                }
                FileInfo destinationFile = new FileInfo(destinationFilePath);
                if (destinationFile.Exists)
                {
                    SetFileCopyed(id, "200", string.Empty);
                }
                else
                {
                    SetFileCopyed(id, "404", "Not Found");
                }
            }
            catch (Exception ex)
            {
                string message = ex.Message;
                SetFileCopyed(id, "-1", message);
                //message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + destinationFilePath + " : " + message;
                //LogManager.LogException(message);
            }

        }

        internal static bool HasIllegalCharacters(string path, bool checkAdditional)
        {
            for (int i = 0; i < path.Length; i++)
            {
                int num2 = path[i];
                if (((num2 == 0x22) || (num2 == 60)) || (((num2 == 0x3e) || (num2 == 0x7c)) || (num2 < 0x20)))//" ' > | space
                {
                    return true;
                }
                if (checkAdditional && ((num2 == 0x3f) || (num2 == 0x2a)))//? *
                {
                    return true;
                }
            }
            return false;
        }

        private static List<string> GetArchiveTables()
        {
            string sql = "SELECT DISTINCT  TableName FROM dbo.Archive_Files ORDER BY TableName";
            DataTable dt = GetData(sql);
            List<string> archiveTables = new List<string>();
            foreach (DataRow row in dt.Rows)
            {
                archiveTables.Add(row["TableName"].ToString());
            }
            return archiveTables;
        }
        static bool HasFinishedDownLoad()
        {
            string sql = "SELECT COUNT(*) FROM dbo.Archive_Files WITH(NOLOCK) WHERE Copyed=0";
            return ExecuteScalar(sql) == 0;
        }

        private static bool SetFileCopyed(string id, string statusCode, string error)
        {
            string sql = string.Format("UPDATE dbo.Archive_Files SET Copyed={0}, CopyDate=GETDATE() ", statusCode);
            if (!string.IsNullOrEmpty(error))
            {
                sql += string.Format(" ,CopyError='{0}' ", error);
            }
            sql += string.Format("  WHERE ID={0}", id);
            return ExecuteCmd(sql);
        }

        private static DataTable GetData(string sql)
        {
            DataTable dt = new DataTable();
            try
            {
                using (SqlConnection con = new SqlConnection(ConnectionString))
                {
                    SqlDataAdapter adapter = new SqlDataAdapter(sql, con);
                    adapter.Fill(dt);
                }
            }
            catch (Exception ex)
            {
                string message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + ex.Message;
                LogManager.LogException(message);
            }
            return dt;
        }

        private static bool ExecuteCmd(string sql)
        {
            int resultCount = 0;
            try
            {
                using (SqlConnection connection = new SqlConnection(ConnectionString))
                {
                    SqlCommand cmd = new SqlCommand(sql, connection);
                    connection.Open();
                    cmd.CommandTimeout = 2 * 60;
                    resultCount = cmd.ExecuteNonQuery();
                    connection.Close();
                }
            }
            catch (Exception ex)
            {
                string message = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + " : " + ex.Message;
                LogManager.LogException(message);
            }
            return resultCount > 0;
        }

        static int ExecuteScalar(string sql)
        {
            int result = 0;
            using (SqlConnection con = new SqlConnection(ConnectionString))
            {
                SqlCommand cmd = new SqlCommand(sql, con);
                cmd.CommandTimeout = 2 * 60;
                con.Open();
                result = Convert.ToInt32(cmd.ExecuteScalar());
                con.Close();
            }
            return result;
        }

        public static string ConnectionString { set; get; }
    }

}

有不对的地方还请大家拍砖！