HTTP多线路断点续传

namespace Microshaoft.Utils
{
    using System;
    using System.IO;
    using System.Net;
    using System.Text;
    using System.Security;
    using System.Threading;
    using System.Collections.Specialized;

    /// <summary>
    /// 记录下载的字节位置
    /// </summary>
    public class DownLoadState
    {
        private string _FileName;

        private string _AttachmentName;
        private int _Position;
        private string _RequestURL;
        private string _ResponseURL;
        private int _Length;

        private byte[] _Data;

        public string FileName
        {
            get
            {
                return _FileName;
            }
        }

        public int Position
        {
            get
            {
                return _Position;
            }
        }

        public int Length
        {
            get
            {
                return _Length;
            }
        }


        public string AttachmentName
        {
            get
            {
                return _AttachmentName;
            }
        }

        public string RequestURL
        {
            get
            {
                return _RequestURL;
            }
        }

        public string ResponseURL
        {
            get
            {
                return _ResponseURL;
            }
        }


        public byte[] Data
        {
            get
            {
                return _Data;
            }
        }

        internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length, byte[] Data)
        {
            this._FileName = FileName;
            this._RequestURL = RequestURL;
            this._ResponseURL = ResponseURL;
            this._AttachmentName = AttachmentName;
            this._Position = Position;
            this._Data = Data;
            this._Length = Length;
        }

        internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length, ThreadCallbackHandler tch)
        {
            this._RequestURL = RequestURL;
            this._ResponseURL = ResponseURL;
            this._FileName = FileName;
            this._AttachmentName = AttachmentName;
            this._Position = Position;
            this._Length = Length;
            this._ThreadCallback = tch;
        }

        internal DownLoadState(string RequestURL, string ResponseURL, string FileName, string AttachmentName, int Position, int Length)
        {
            this._RequestURL = RequestURL;
            this._ResponseURL = ResponseURL;
            this._FileName = FileName;
            this._AttachmentName = AttachmentName;
            this._Position = Position;
            this._Length = Length;
        }

        private ThreadCallbackHandler _ThreadCallback;

        public HttpWebClient httpWebClient
        {
            get
            {
                return this._hwc;
            }
            set
            {
                this._hwc = value;
            }
        }

        internal Thread thread
        {
            get
            {
                return _thread;
            }
            set
            {
                _thread = value;
            }
        }

        private HttpWebClient _hwc;
        private Thread _thread;

        //
        internal void StartDownloadFileChunk()
        {
            if (this._ThreadCallback != null)
            {
                this._ThreadCallback(this._RequestURL, this._FileName, this._Position, this._Length);
                this._hwc.OnThreadProcess(this._thread);
            }
        }

    }

    //委托代理线程的所执行的方法签名一致
    public delegate void ThreadCallbackHandler(string S, string s, int I, int i);

    //异常处理动作
    public enum ExceptionActions
    {
        Throw,
        CancelAll,
        Ignore,
        Retry
    }

    /// <summary>
    /// 包含 Exception 事件数据的类
    /// </summary>
    public class ExceptionEventArgs : System.EventArgs
    {
        private System.Exception _Exception;
        private ExceptionActions _ExceptionAction;

        private DownLoadState _DownloadState;

        public DownLoadState DownloadState
        {
            get
            {
                return _DownloadState;
            }
        }

        public Exception Exception
        {
            get
            {
                return _Exception;
            }
        }

        public ExceptionActions ExceptionAction
        {
            get
            {
                return _ExceptionAction;
            }
            set
            {
                _ExceptionAction = value;
            }
        }

        internal ExceptionEventArgs(System.Exception e, DownLoadState DownloadState)
        {
            this._Exception = e;
            this._DownloadState = DownloadState;
        }
    }

    /// <summary>
    /// 包含 DownLoad 事件数据的类
    /// </summary>
    public class DownLoadEventArgs : System.EventArgs
    {
        private DownLoadState _DownloadState;

        public DownLoadState DownloadState
        {
            get
            {
                return _DownloadState;
            }
        }

        public DownLoadEventArgs(DownLoadState DownloadState)
        {
            this._DownloadState = DownloadState;
        }

    }

    public class ThreadProcessEventArgs : System.EventArgs
    {
        private Thread _thread;

        public Thread thread
        {
            get
            {
                return this._thread;
            }
        }

        public ThreadProcessEventArgs(Thread thread)
        {
            this._thread = thread;
        }

    }

    /// <summary>
    /// 支持断点续传多线程下载的类
    /// </summary>
    public class HttpWebClient
    {
        private static object _SyncLockObject = new object();

        public delegate void DataReceiveEventHandler(HttpWebClient Sender, DownLoadEventArgs e);

        public event DataReceiveEventHandler DataReceive; //接收字节数据事件

        public delegate void ExceptionEventHandler(HttpWebClient Sender, ExceptionEventArgs e);

        public event ExceptionEventHandler ExceptionOccurrs; //发生异常事件

        public delegate void ThreadProcessEventHandler(HttpWebClient Sender, ThreadProcessEventArgs e);

        public event ThreadProcessEventHandler ThreadProcessEnd; //发生多线程处理完毕事件


        private int _FileLength; //下载文件的总大小

        public int FileLength
        {
            get
            {
                return _FileLength;
            }
        }

        /// <summary>
        /// 分块下载文件
        /// </summary>
        /// <param name="Address">URL 地址</param>
        /// <param name="FileName">保存到本地的路径文件名</param>
        /// <param name="ChunksCount">块数,线程数</param>
        public void DownloadFile(string Address, string FileName, int ChunksCount)
        {
            int p = 0; // position
            int s = 0; // chunk size
            string a = null;
            HttpWebRequest hwrq;
            HttpWebResponse hwrp = null;
            try
            {
                hwrq = (HttpWebRequest)WebRequest.Create(this.GetUri(Address));
                hwrp = (HttpWebResponse)hwrq.GetResponse();
                long L = hwrp.ContentLength;

                hwrq.Credentials = this.m_credentials;

                L = ((L == -1) || (L > 0x7fffffff)) ? ((long)0x7fffffff) : L; //Int32.MaxValue 该常数的值为 2,147,483,647; 即十六进制的 0x7FFFFFFF

                int l = (int)L;

                this._FileLength = l;

                //    在本地预定空间(竟然在多线程下不用先预定空间)
                //    FileStream sw = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
                //    sw.Write(new byte[l], 0, l);
                //    sw.Close();
                //    sw = null;

                bool b = (hwrp.Headers["Accept-Ranges"] != null & hwrp.Headers["Accept-Ranges"] == "bytes");
                a = hwrp.Headers["Content-Disposition"]; //attachment
                if (a != null)
                {
                    a = a.Substring(a.LastIndexOf("filename=") + 9);
                }
                else
                {
                    a = FileName;
                }

                int ss = s;
                if (b)
                {
                    s = l / ChunksCount;
                    if (s < 2 * 64 * 1024) //块大小至少为 128 K 字节
                    {
                        s = 2 * 64 * 1024;
                    }
                    ss = s;
                    int i = 0;
                    while (l > s)
                    {
                        l -= s;
                        if (l < s)
                        {
                            s += l;
                        }
                        if (i++ > 0)
                        {
                            DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s, new ThreadCallbackHandler(this.DownloadFileChunk));
                            //       单线程下载
                            //       x.StartDownloadFileChunk();

                            x.httpWebClient = this;
                            //多线程下载
                            Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk));
                            //this.OnThreadProcess(t);
                            t.Start();

                        }
                        p += s;
                    }
                    s = ss;
                    byte[] buffer = this.ResponseAsBytes(Address, hwrp, s, FileName);
                    this.OnThreadProcess(Thread.CurrentThread);

                    //    lock (_SyncLockObject)
                    //    {
                    //     this._Bytes += buffer.Length;
                    //    }
                }
            }
            catch (Exception e)
            {
                ExceptionActions ea = ExceptionActions.Throw;
                if (this.ExceptionOccurrs != null)
                {
                    DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p, s);
                    ExceptionEventArgs eea = new ExceptionEventArgs(e, x);
                    ExceptionOccurrs(this, eea);
                    ea = eea.ExceptionAction;
                }

                if (ea == ExceptionActions.Throw)
                {
                    if (!(e is WebException) && !(e is SecurityException))
                    {
                        throw new WebException("net_webclient", e);
                    }
                    throw;
                }
            }

        }

        internal void OnThreadProcess(Thread t)
        {
            if (ThreadProcessEnd != null)
            {
                ThreadProcessEventArgs tpea = new ThreadProcessEventArgs(t);
                ThreadProcessEnd(this, tpea);
            }
        }

        /// <summary>
        /// 下载一个文件块,利用该方法可自行实现多线程断点续传
        /// </summary>
        /// <param name="Address">URL 地址</param>
        /// <param name="FileName">保存到本地的路径文件名</param>
        /// <param name="Length">块大小</param>
        public void DownloadFileChunk(string Address, string FileName, int FromPosition, int Length)
        {
            HttpWebResponse hwrp = null;
            string a = null;
            try
            {
                //this._FileName = FileName;
                HttpWebRequest hwrq = (HttpWebRequest)WebRequest.Create(this.GetUri(Address));
                //hwrq.Credentials = this.m_credentials;
                hwrq.AddRange(FromPosition);
                hwrp = (HttpWebResponse)hwrq.GetResponse();
                a = hwrp.Headers["Content-Disposition"]; //attachment
                if (a != null)
                {
                    a = a.Substring(a.LastIndexOf("filename=") + 9);
                }
                else
                {
                    a = FileName;
                }

                byte[] buffer = this.ResponseAsBytes(Address, hwrp, Length, FileName);
                //   lock (_SyncLockObject)
                //   {
                //    this._Bytes += buffer.Length;
                //   }
            }
            catch (Exception e)
            {
                ExceptionActions ea = ExceptionActions.Throw;
                if (this.ExceptionOccurrs != null)
                {
                    DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, FromPosition, Length);
                    ExceptionEventArgs eea = new ExceptionEventArgs(e, x);
                    ExceptionOccurrs(this, eea);
                    ea = eea.ExceptionAction;
                }

                if (ea == ExceptionActions.Throw)
                {
                    if (!(e is WebException) && !(e is SecurityException))
                    {
                        throw new WebException("net_webclient", e);
                    }
                    throw;
                }
            }
        }

        internal byte[] ResponseAsBytes(string RequestURL, WebResponse Response, long Length, string FileName)
        {
            string a = null; //AttachmentName
            int P = 0; //整个文件的位置指针
            int num2 = 0;
            try
            {
                a = Response.Headers["Content-Disposition"]; //attachment
                if (a != null)
                {
                    a = a.Substring(a.LastIndexOf("filename=") + 9);
                }

                long num1 = Length; //Response.ContentLength;
                bool flag1 = false;
                if (num1 == -1)
                {
                    flag1 = true;
                    num1 = 0x10000; //64k
                }
                byte[] buffer1 = new byte[(int)num1];


                int p = 0; //本块的位置指针

                string s = Response.Headers["Content-Range"];
                if (s != null)
                {
                    s = s.Replace("bytes ", "");
                    s = s.Substring(0, s.IndexOf("-"));
                    P = Convert.ToInt32(s);
                }
                int num3 = 0;

                Stream S = Response.GetResponseStream();
                do
                {
                    num2 = S.Read(buffer1, num3, ((int)num1) - num3);

                    num3 += num2;
                    if (flag1 && (num3 == num1))
                    {
                        num1 += 0x10000;
                        byte[] buffer2 = new byte[(int)num1];
                        Buffer.BlockCopy(buffer1, 0, buffer2, 0, num3);
                        buffer1 = buffer2;
                    }

                    //    lock (_SyncLockObject)
                    //    {
                    //     this._bytes += num2;
                    //    }
                    if (num2 > 0)
                    {
                        if (this.DataReceive != null)
                        {
                            byte[] buffer = new byte[num2];
                            Buffer.BlockCopy(buffer1, p, buffer, 0, buffer.Length);
                            DownLoadState dls = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2, buffer);
                            DownLoadEventArgs dlea = new DownLoadEventArgs(dls);
                            //触发事件
                            this.OnDataReceive(dlea);
                            //System.Threading.Thread.Sleep(100);

                        }
                        p += num2; //本块的位置指针
                        P += num2; //整个文件的位置指针
                    }
                    else
                    {
                        break;
                    }

                }
                while (num2 != 0);

                S.Close();
                S = null;
                if (flag1)
                {
                    byte[] buffer3 = new byte[num3];
                    Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3);
                    buffer1 = buffer3;
                }
                return buffer1;
            }
            catch (Exception e)
            {
                ExceptionActions ea = ExceptionActions.Throw;
                if (this.ExceptionOccurrs != null)
                {
                    DownLoadState x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2);
                    ExceptionEventArgs eea = new ExceptionEventArgs(e, x);
                    ExceptionOccurrs(this, eea);
                    ea = eea.ExceptionAction;
                }

                if (ea == ExceptionActions.Throw)
                {
                    if (!(e is WebException) && !(e is SecurityException))
                    {
                        throw new WebException("net_webclient", e);
                    }
                    throw;
                }
                return null;
            }
        }