Asp.net 2.0 文件下载[支持多线程, 断点续传功能](示例代码下载)

(一) . 概述

        最近做了个C/S文件下载工具, 支持多任务, 多线程和断点续传功能. 其中部分代码是从网上找来的, 自己改了

许多Thread Bug, 并增加多任务, 断点续传等功能.  

        由于公司具有代码所有权, 不能将源代码共享.  自己对比较Asp.net感兴趣, 业余时间自己做了个简单的, 基于

Asp.net 2.0的, 目前能够执行对一个文件的下载任务, 但已经实现了多线程, 断点续传功能.  根据需要您可以增加

多任务 功能, 分享一下, 互相学习!  互相借鉴!

       时间仓促, 此程序还没有做很多参数方面的优化. 可以作参考用.

              

(二).运行效果

 

(三). 代码

    1. 核心 DownLoadState.cs 文件代码

 

/// <summary>

   /// Author: [ ChengKing(ZhengJian) ]

    /// Blog:   Http://blog.csdn.net/ChengKing

    /// 注：从网上找了个优秀代码

    /// 扩展如下功能:

    ///   1. 解决一些线程相关的Bug;

    ///   2.扩展用控制文件实现断点续传功能.

    /// </summary>

    namespace DownLoadComponent

   {

       /// <summary>

       /// 多线程辅助类(Add by ChengKing)

       /// </summary>

       public class Task

       {

           string _FromFileName;

           string _ToFileName;

           int _ThreadNum;

  

           public Task(string FromFileName, string ToFileName, int ThreadNum)

           {

               this._FromFileName = FromFileName;

               this._ToFileName = ToFileName;

               this._ThreadNum = ThreadNum;

           }

  

           public string FromFileName

           {

               get

               {

                   return _FromFileName;

               }

               set

               {

                   _FromFileName = value;

               }

           }

           public string ToFileName

           {

               get

               {

                   return _ToFileName;

               }

               set

               {

                   _ToFileName = value;

               }

           }

           public int ThreadNum

           {

               get

               {

                   return _ThreadNum;

               }

               set

               {

                   _ThreadNum = value;

               }

           }

       }

  

       /// <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;

 

          //

          internal void StartDownloadFileChunk()

          {

              if (this._ThreadCallback != null)

              {

                  this._ThreadCallback(this._RequestURL, this._FileName, this._Position, this._Length);

              }

          }

 

      }

 

      //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;

         }

 

     }

 

     /// <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

 

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

 

         public static ArrayList threads;

 

         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));

                 //hwrq.Timeout = 20000000;

                 //if (hwrq.HaveResponse == false)

                 //    return;

                 //hwrq.ProtocolVersion =HttpVersion.Version10;

                 //WebProxy wp = WebProxy.GetDefaultProxy();

                 //hwrq.Proxy = wp;

                 hwrq.Method = "GET";

                try

                 {

                     hwrp = (HttpWebResponse)hwrq.GetResponse();

                 }

                 catch (Exception e)

                 {

                     throw new Exception(e.Message);

                 }

 

                 long L = hwrp.ContentLength;

 

                 //如果文件太小, 就不用分多线程, 用一个线程下载即可. (目前控制在800K)

                 //if (L < 800000)

                 //{

                 //    ChunksCount = 1;

                 //}

 

                 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;

 

                 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)

                 {

                     if (ExistControlFile(FileName)) //是否存在文件

                     {

                         string[] strBlocks = this.ReadInfFromControlFile(FileName).Split(new char[2] { '/r', '/n' });

                         for (int i = 0; i < strBlocks.Length; i++)

                         {

                             if (strBlocks[i].Trim().Length != 0 && strBlocks[i].Substring(strBlocks[i].Length - 1) == "0")

                             {

                                 string[] strRecord = strBlocks[i].Split(',');

                                 int p2 = int.Parse(strRecord[0]);

                                 int s2 = int.Parse(strRecord[1]);

                                 DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, p2, s2, new ThreadCallbackHandler(this.DownloadFileChunk));

                                  Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk));

                                 if (threads == null)

                                 {

                                     threads = new ArrayList();

                                 }

                                 threads.Add(t);

                                 t.Start();

                             }

 

 

                         }

 

                     }

                     else

                     {

                         //建立控制文件

                         FileStream fs = File.Create(this.GetControlFileName(FileName));

                         fs.Close();

 

                         if (File.Exists(FileName))

                         {

                             FileInfo fi = new FileInfo(FileName);

                             if (fi.Length == L)

                             {

                                 this.AddendInfToControlFile(FileName, 0, 0);

                                 this.UpdateControlFile(FileName, 0, 0);

                                 return;

                             }

                         }

 

                         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));

 

                                 AddendInfToControlFile(FileName, p, s);

                                 Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk));

                                 if (threads == null)

                                 {

                                     threads = new ArrayList();

                                 }

                                 threads.Add(t);

                                 t.Start();

 

                             }

                             p += s;

                         }

                         s = ss;

 

                         AddendInfToControlFile(FileName, 0, s);

                         DownLoadState x1 = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, 0, s, new ThreadCallbackHandler(this.DownloadFileChunk));

                         Thread t2 = new Thread(new ThreadStart(x1.StartDownloadFileChunk));

                         if (threads == null)

                         {

                             threads = new ArrayList();

                         }

                         threads.Add(t2);

                       t2.Start();

                     }

                 }

                 //如果服务器不支持断点续传(Accept-Range), 则使用单线程下载

                 else

                 {

                     AddendInfToControlFile(FileName, 0, l);

                     DownLoadState x = new DownLoadState(Address, hwrp.ResponseUri.AbsolutePath, FileName, a, 0, l, new ThreadCallbackHandler(this.DownloadFileChunk));

                     Thread t = new Thread(new ThreadStart(x.StartDownloadFileChunk));

                     if (threads == null)

                     {

                         threads = new ArrayList();

                     }

                     threads.Add(t);

                     t.Start();

                 }

             }

             catch (Exception e)

             {

                 //if (blnReturn == true)

               //{

                 //    return;

                 //}

 

                 ExceptionActions ea = ExceptionActions.Throw;

                 if (ea == ExceptionActions.Throw)

                 {

                     if (!(e is WebException) && !(e is SecurityException))

                     {

                         throw new WebException("net_webclient", e);

                     }

                     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;

                 //}

 

             }

 

         }

 

         #region 操作控制文件(By King Zheng)

 

         /// <summary>

         /// 插入文件块信息到控制文件(Add by ChengKing)

         /// </summary>

         /// <param name="FileName"></param>

         /// <param name="Position"></param>

         /// <param name="Length"></param>

         private void AddendInfToControlFile(string FileName, int Position, int Length)

         {

 

 

             try

             {

                 lock (_SyncLockObject)

                 {

                     string strControlFile = GetControlFileName(FileName);

 

 

                     //if (File.Exists(strControlFile) == false)

                     //{

                     //    return;

                     //}

 

                     using (StreamWriter sw = new StreamWriter(strControlFile, true, Encoding.Default))

                     {

                         //sw.NewLine = "$";

                         sw.WriteLine(Position.ToString() + "," + Length.ToString() + "," + "0");

                     }

                     //using (System.IO.FileStream sw = new System.IO.FileStream(strControlFile, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.ReadWrite, System.IO.FileShare.ReadWrite))

                     //{

                     //    //sw.Position = e.DownloadState.Position;

                   //    sw.Write(Position.ToString() + "," + Length.ToString() + "," + "0");

                     //    sw.Close();

                     //}

 

 

 

                 }

             }

             catch (Exception e)

             {

                 throw new Exception("写控制文件出错!" + e.Message);

             }

 

         }

 

         /// <summary>

         /// 更新控制文件(Add by ChengKing)

         /// </summary>

         /// <param name="FileName"></param>

         /// <param name="Position"></param>

         /// <param name="Length"></param>

         private void UpdateControlFile(string FileName, int Position, int Length)

         {

             try

             {

                 lock (_SyncLockObject)

                 {

                     string strControlFile = GetControlFileName(FileName);

 

 

                     //if (File.Exists(strControlFile) == false)

                     //{

                     //    return;

                     //}

 

                     string s = null;

                     using (StreamReader sr = new System.IO.StreamReader(strControlFile))

                     {

                         s = sr.ReadToEnd();

                         s = s.Replace(Position.ToString() + "," + Length.ToString() + "," + "0", Position.ToString() + "," + Length.ToString() + "," + "1");

                    }

                     using (StreamWriter sw = new StreamWriter(strControlFile, false, Encoding.Default))

                     {

                         sw.WriteLine(s);

                     }

                 }

             }

             catch (Exception e)

             {

                 throw new Exception("更新控制文件出错!" + e.Message);

             }

 

         }

 

         /// <summary>

         /// 读取所有信息从控制文件(Add by ChengKing)

         /// </summary>

         /// <param name="FileName"></param>

         /// <returns></returns>

         private string ReadInfFromControlFile(string FileName)

         {

             try

             {

                 lock (_SyncLockObject)

                 {

                     string strControlFile = GetControlFileName(FileName);

 

                     string s = null;

                     using (StreamReader sr = new System.IO.StreamReader(strControlFile))

                     {

                         s = sr.ReadToEnd();

 

                     }

                     return s;

                 }

             }

             catch (Exception e)

             {

                 throw new Exception("读控制文件出错!" + e.Message);

             }

         }

 

         /// <summary>

         /// 根据目标文件名得到控制文件名(Add by ChengKing)

         /// </summary>

         /// <param name="FileName"></param>

         /// <returns></returns>

         public string GetControlFileName(string FileName)

         {

             string strPath = Path.GetDirectoryName(FileName);

 

             //string strFileNameWithoutExtension = Path.GetFileNameWithoutExtension(FileName);

             string strFileNameWithoutExtension = Path.GetFileName(FileName);

             string strControlFile = Path.Combine(strPath, strFileNameWithoutExtension + "_Control.txt");

             return strControlFile;

         }

 

         /// <summary>

         /// 判断控制文件是否存在

         /// </summary>

         /// <param name="FileName"></param>

         /// <returns></returns>

         private bool ExistControlFile(string FileName)

         {

             string strControlFile = GetControlFileName(FileName);

             if (File.Exists(strControlFile))

             {

                 return true;

             }

             return false;

         }

 

         /// <summary>

         /// 判断控制文件是否完成

         /// </summary>

         /// <param name="strControlFile"></param>

         /// <returns></returns>

         public bool JudgeControlFileIfFinished(string strControlFile)

         {

             try

             {

                 string s = null;

                 lock (_SyncLockObject)

                 {

                     using (StreamReader sr = new System.IO.StreamReader(strControlFile))

                     {

                         s = sr.ReadToEnd();

                     }

                 }

                 if (s + String.Empty == String.Empty)

                 {

                     return false;

                 }

                 string[] strBlocks = s.Split(new char[2] { '/r', '/n' });

                 for (int i = 0; i < strBlocks.Length; i++)

                 {

                     if (strBlocks[i].Trim().Length != 0 && strBlocks[i].Substring(strBlocks[i].Length - 1) == "0")

                     {

                         return false;

                     }

                 }

                 return true;

 

             }

             catch (Exception e)

             {

                 throw new Exception("判断控制文件是否完成时, 读取文件出错!" + e.Message);

             }

         }

 

         /// <summary>

         /// 删除控制文件(Add by ChengKing)

         /// </summary>

         /// <param name="strControlFile"></param>

         /// <returns></returns>

         public bool DeleteControlFile(string strControlFile)

         {

             try

             {

                 lock (_SyncLockObject)

                 {

                     if (File.Exists(strControlFile))

                     {

                         File.Delete(strControlFile);

                     }

                 }

                 return true;

             }

             catch (Exception e)

             {

                 throw new Exception("删除控制文件出错!" + e.Message);

             }

         }

 

         #endregion

 

         /// <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();

 

                 //hwrp.Headers.Add("Content-Range", FromPosition.ToString());  //Test

 

                 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;

             int num3 = 0;

             int intFrom = 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[(long)num1];

 

 

                 int p = 0; //本块的位置指针

 

                 string s = Response.Headers["Content-Range"];

                 //string s = hwrq.Headers["Range"];

 

                 if (s != null)

                 {

                     s = s.Replace("bytes ", "");

                     s = s.Substring(0, s.IndexOf("-"));

                     P = Convert.ToInt32(s);

                     intFrom = P;

 

                 }

 

                 //int num3 = 0;

 

                 Stream S = Response.GetResponseStream();

 

                 int count = 0;

 

                 int bufferSize = 65535; //允许读取的最大字节

 

                 int times;

                  do

                 {

                     times = 0;

 

                     //num2 = S.Read(buffer1, num3, ((int)num1) - num3);

 

                     //限制最大读取字节

                      if (bufferSize < ((int)num1) - num3)

                     {

                         num2 = S.Read(buffer1, num3, bufferSize);

                     }

                     else

                     {

                         num2 = S.Read(buffer1, num3, ((int)num1) - num3);

                     }

 

                     //网络短时间的不稳定

                     if (num2 == 0)

                     {

                         Thread.Sleep(50);

                         times++;

 

                         if (times > 100)

                         {

                             throw new Exception("网络传输层错误");

                         }

 

                     }

 

                     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);

 

                 count++;

 

                 int c = count;

 

                 S.Close();

                 S = null;

                 if (flag1)

                 {

                     byte[] buffer3 = new byte[num3];

                     Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3);

                      buffer1 = buffer3;

                 }

 

                 UpdateControlFile(FileName, intFrom, (int)Length);

 

                 return buffer1;

             }

             catch (Exception e)

             {

                 ExceptionActions ea = ExceptionActions.Throw;

                 if (this.ExceptionOccurrs != null)

                 {

                     Thread.Sleep(100);

                     //DownLoadState x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, num2);

                     //DownLoadState x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, (int)(Length - num3));

                     DownLoadState x = new DownLoadState(RequestURL, Response.ResponseUri.AbsolutePath, FileName, a, P, (int)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;

                }

                 return null;

             }

         }

 

         private void OnDataReceive(DownLoadEventArgs e)

         {

             //触发数据到达事件

             DataReceive(this, e);

         }

 

         public byte[] UploadFile(string address, string fileName)

         {

             return this.UploadFile(address, "POST", fileName, "file");

         }

 

         public string UploadFileEx(string address, string method, string fileName, string fieldName)

         {

             return Encoding.ASCII.GetString(UploadFile(address, method, fileName, fieldName));

         }

 

         public byte[] UploadFile(string address, string method, string fileName, string fieldName)

         {

             byte[] buffer4;

             FileStream stream1 = null;

             try

             {

                 fileName = Path.GetFullPath(fileName);

                 string text1 = "---------------------" + DateTime.Now.Ticks.ToString("x");

 

                string text2 = "application/octet-stream";

 

                stream1 = new FileStream(fileName, FileMode.Open, FileAccess.Read);

                 WebRequest request1 = WebRequest.Create(this.GetUri(address));

                 request1.Credentials = this.m_credentials;

                 request1.ContentType = "multipart/form-data; boundary=" + text1;

 

                 request1.Method = method;

                 string[] textArray1 = new string[7] { "--", text1, "/r/nContent-Disposition: form-data; name=/"" + fieldName + "/"; filename=/"", Path.GetFileName(fileName), "/"/r/nContent-Type: ", text2, "/r/n/r/n" };

                 string text3 = string.Concat(textArray1);

                 byte[] buffer1 = Encoding.UTF8.GetBytes(text3);

                  byte[] buffer2 = Encoding.ASCII.GetBytes("/r/n--" + text1 + "/r/n");

                 long num1 = 0x7fffffffffffffff;

                 try

                 {

                     num1 = stream1.Length;

                     request1.ContentLength = (num1 + buffer1.Length) + buffer2.Length;

                 }

                 catch

                 {

                 }

                 byte[] buffer3 = new byte[Math.Min(0x2000, (int)num1)];

                  using (Stream stream2 = request1.GetRequestStream())

                 {

                     int num2;

                     stream2.Write(buffer1, 0, buffer1.Length);

                     do

                     {

                         num2 = stream1.Read(buffer3, 0, buffer3.Length);

                         if (num2 != 0)

                        {

                             stream2.Write(buffer3, 0, num2);

                         }

                     }

                     while (num2 != 0);

                     stream2.Write(buffer2, 0, buffer2.Length);

                 }

                 stream1.Close();

                 stream1 = null;

                 WebResponse response1 = request1.GetResponse();

 

                 buffer4 = this.ResponseAsBytes(response1);

             }

             catch (Exception exception1)

             {

                 if (stream1 != null)

                 {

                     stream1.Close();

                     stream1 = null;

                 }

                 if (!(exception1 is WebException) && !(exception1 is SecurityException))

                 {

                     //throw new WebException(SR.GetString("net_webclient"), exception1);

                     throw new WebException("net_webclient", exception1);

                 }

                 throw;

             }

             return buffer4;

         }

 

          private byte[] ResponseAsBytes(WebResponse response)

         {

             int num2;

             long num1 = response.ContentLength;

             bool flag1 = false;

             if (num1 == -1)

             {

                 flag1 = true;

                 num1 = 0x10000;

             }

            byte[] buffer1 = new byte[(int)num1];

             Stream stream1 = response.GetResponseStream();

             int num3 = 0;

             do

             {

                 num2 = stream1.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;

                 }

             }

             while (num2 != 0);

             stream1.Close();

             if (flag1)

             {

                 byte[] buffer3 = new byte[num3];

               Buffer.BlockCopy(buffer1, 0, buffer3, 0, num3);

                 buffer1 = buffer3;

             }

             return buffer1;

         }

 

         private NameValueCollection m_requestParameters;

         private Uri m_baseAddress;

         private ICredentials m_credentials = CredentialCache.DefaultCredentials;

 

         public ICredentials Credentials

         {

             get

             {

                 return this.m_credentials;

             }

             set

             {

                 this.m_credentials = value;

             }

         }

 

         public NameValueCollection QueryString

         {

             get

             {

                 if (this.m_requestParameters == null)

                 {

                     this.m_requestParameters = new NameValueCollection();

                 }

                 return this.m_requestParameters;

             }

             set

             {

                 this.m_requestParameters = value;

             }

         }

 

         public string BaseAddress

         {

            get

             {

                 if (this.m_baseAddress != null)

                 {

                     return this.m_baseAddress.ToString();

                 }

                 return string.Empty;

             }

             set

             {

               if ((value == null) || (value.Length == 0))

                 {

                     this.m_baseAddress = null;

                 }

                 else

                 {

                     try

                     {

                         this.m_baseAddress = new Uri(value);

                     }

                   catch (Exception exception1)

                     {

                         throw new ArgumentException("value", exception1);

                     }

                 }

             }

         }

 

         public Uri GetUri(string path)

         {

            Uri uri1;

             try

             {

                 if (this.m_baseAddress != null)

                 {

                     uri1 = new Uri(this.m_baseAddress, path);

                 }

                 else

                 {

                     uri1 = new Uri(path);

                }

                 if (this.m_requestParameters == null)

                 {

                     return uri1;

                 }

                 StringBuilder builder1 = new StringBuilder();

                 string text1 = string.Empty;

                 for (int num1 = 0; num1 < this.m_requestParameters.Count; num1++)

                 {

                     builder1.Append(text1 + this.m_requestParameters.AllKeys[num1] + "=" + this.m_requestParameters[num1]);

                     text1 = "&";

                 }

                 UriBuilder builder2 = new UriBuilder(uri1);

                 builder2.Query = builder1.ToString();

                 uri1 = builder2.Uri;

             }

             catch (UriFormatException)

             {

                 uri1 = new Uri(Path.GetFullPath(path));

             }

            return uri1;

         }

 

     }

 

 }

 

 

    2.页面 Default.aspx 文件 代码

  <html xmlns="http://www.w3.org/1999/xhtml" >

<head runat="server">

  <script language="javascript">

     mainLoop = function()

       {

       var objPath = document.getElementById("TextBox2");

         var blnValue = _Default.CheckControlFiles(objPath.value);                      

             //a.value = a.value + blnValue.value;

             if( blnValue.value == true)

            {

                 var returnvalue=setTimeout('mainLoop()', 1000);           

             }

             else

             {

                 var objStatus = document.getElementById("Label1");

                 objStatus.innerText = "状态: 下载完成!";

                

                 var btOK = document.getElementById("btOK");

                 btOK.disabled = "";             

                

                 var btCancel = document.getElementById("btCancel");

                 btCancel.disabled = "disabled";

                                

             }

         }   

        

    

     </script>

 

 </head>

 <body>

     <form id="frmTest" runat="server" >

"><tr><td style="height: 259px">

         <br />

         <strong><span style="color: #000099">

         下载组件:

         <br />

         1. 支持多线程: &nbsp;多个线程某时刻下载同一个文件的不同块.<br />

         2. 断点续传: &nbsp;如果下载了一个文件的某些块(一半), 则下次<br />

            &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 下载时只需下载未完成的块;

             &nbsp;文件块的下载状<br />

             &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 态用控制文件记录.

             块下载完成的先后顺序不<br />

             &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 一定是连续的.<br />

         </span></strong>

         <br />

         <table style="width: 379px">

             <tr>

                 <td colspan="1" style="width: 87px">

                    Source</td>

                 <td colspan="2" style="width: 326px">

         <asp:TextBox ID="TextBox1" runat="server" Width="391px">http://www.</asp:TextBox></td>

             </tr>

             <tr>

                 <td colspan="1" style="width: 87px">

                     Location</td>

                 <td colspan="2" style="width: 326px">

                     <asp:TextBox ID="TextBox2" runat="server" Width="391px">D:/Documents and Settings/zhengjian/桌面/TestDownLoads/</asp:TextBox></td>

             </tr>

            <tr>

                 <td colspan="1" style="width: 87px">

                     Threads</td>

                 <td colspan="2" style="width: 326px">

                     <asp:TextBox ID="TextBox3" runat="server" Width="390px">10</asp:TextBox></td>

             </tr>

         </table>

         <br />

         <asp:Button ID="btOK" runat="server" Text="下载" Height="42px" Width="108px" OnClick="btOK_Click" />&nbsp;

         &nbsp;<asp:Button ID="btCancel" runat="server" OnClick="btCancel_Click" Text="取消/暂停" Height="42px" Width="108px" Enabled="False" /><br />

       <br />

         <asp:Label ID="Label1" runat="server" Height="32px" Text="状态: 未开始下载" Width="227px" Font-Bold="True" ForeColor="#8080FF"></asp:Label><br />

         </td></tr></table>

         <script language=javascript>

             mainLoop();

         </script>

     </form>

 </body>

 </html>

   3. 页面后台文件 Default.aspx.cs代码

   /// <summary>

 /// Author: [ ChengKing(ZhengJian) ]

 /// Blog:   Http://blog.csdn.net/ChengKing

 /// 注：从网上找了个优秀代码

 /// 扩展如下功能:

 ///   1. 解决一些线程相关的Bug;

 ///   2.扩展用控制文件实现断点续传功能.

 /// </summary>

 public partial class _Default : System.Web.UI.Page

{   

      //全局变量

     private static object _SyncLockObject = new object();

 

     protected void Page_Load(object sender, EventArgs e)

     {

         Utility.RegisterTypeForAjax(typeof(_Default));      

         //this.TextBox1.Text = "http://download.csdn.net/filedown/aHR0cDovL2Rvd25sb2FkMS5jc2RuLm5ldC9kb3duMy8yMDA3MDUwNy8wNzE4MDIwNzY4OC5yYXI=!177258";

        

        

         this.TextBox1.Text = "http://www.cnblogs.com/Files/ChengKing/智能象棋游戏(T1).rar";

     }

     protected void btOK_Click(object sender, EventArgs e)

     {

         this.Label1.Text = "状态: 正在下载 ";

        

         DownLoadComponent.HttpWebClient x = new DownLoadComponent.HttpWebClient();

 

         //注册 DataReceive　事件

         x.DataReceive += new DownLoadComponent.HttpWebClient.DataReceiveEventHandler(this.x_DataReceive);

         //注册 ExceptionOccurrs　事件

         x.ExceptionOccurrs += new DownLoadComponent.HttpWebClient.ExceptionEventHandler(this.x_ExceptionOccurrs);

 

         string Source = this.TextBox1.Text.Trim();

         string FileName = Source.Substring(Source.LastIndexOf("/") + 1);

         string Location= System.IO.Path.Combine( this.TextBox2.Text.Trim() , FileName);

        

         //F: 源服务器文件;  _f: 保存路径;  10: 自设定一个文件有几个线程下载.

         x.DownloadFile(Source,Location , int.Parse(this.TextBox3.Text));

 

        //Response.Write("正在下载文件 ");

         this.btOK.Enabled = false;

         this.btCancel.Enabled = true;

     }

 

     private void x_DataReceive(DownLoadComponent.HttpWebClient Sender, DownLoadComponent.DownLoadEventArgs e)

     {

 

         string f = e.DownloadState.FileName;

         if (e.DownloadState.AttachmentName != null)

           f = System.IO.Path.GetDirectoryName(f) + @"/" + e.DownloadState.AttachmentName;      

         

         using (System.IO.FileStream sw = new System.IO.FileStream(f, System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.ReadWrite, System.IO.FileShare.ReadWrite))

         {

             sw.Position = e.DownloadState.Position;               

             sw.Write(e.DownloadState.Data, 0, e.DownloadState.Data.Length);

             sw.Close();

         }           

     }  

 

     private void x_ExceptionOccurrs(DownLoadComponent.HttpWebClient Sender, DownLoadComponent.ExceptionEventArgs e)

     {

         System.Console.WriteLine(e.Exception.Message);

         //发生异常重新下载相当于断点续传,你可以自己自行选择处理方式或自行处理

         DownLoadComponent.HttpWebClient x = new DownLoadComponent.HttpWebClient();

         x.DataReceive += new DownLoadComponent.HttpWebClient.DataReceiveEventHandler(this.x_DataReceive);

         //订阅 ExceptionOccurrs　事件

         //x.ExceptionOccurrs += new DownLoadComponent.HttpWebClient.ExceptionEventHandler(this.x_ExceptionOccurrs);

 

         x.DownloadFileChunk(e.DownloadState.RequestURL, e.DownloadState.FileName, e.DownloadState.Position, e.DownloadState.Length);

        e.ExceptionAction = DownLoadComponent.ExceptionActions.Ignore;

     }

     protected void btCancel_Click(object sender, EventArgs e)

     {

         if (DownLoadComponent.HttpWebClient.threads != null)

         {

             foreach (Thread t in DownLoadComponent.HttpWebClient.threads)

             {

                 if (t.IsAlive)

                 {

                    t.Abort();

                 }

             }

 

             DownLoadComponent.HttpWebClient.threads.Clear();

         }

         System.Diagnostics.Process myproc = new System.Diagnostics.Process();

         Process[] procs = (Process[])Process.GetProcessesByName("DW20.exe");  //得到所有打开的进程

         try

         {

           foreach (Process proc in procs)

             {

                 if (proc.CloseMainWindow() == false)

                 {

                     proc.Kill();

                 }

             }

         }

         catch

         { }

        KillAllThreads();

         this.btOK.Enabled = true;

         this.btCancel.Enabled = false;

         GC.Collect();

       

     }

 

     /// <summary>

     /// 定期检查控制文件

     /// </summary>

    /// <param name="str"></param>

     /// <returns>是否还继续监视(1: 正在下载中，继续监视; 0: 表示已经下载完毕,不用再检视)</returns>

     [AjaxMethod()]// or [AjaxPro.AjaxMethod]

     public bool CheckControlFiles(string strObjPath)

     {

         if (!WhetherDownloadFinished(strObjPath))

         {

             return true;

         }

         return false;

    }

 

     private bool WhetherDownloadFinished(string strObjPath)

     {

         DirectoryInfo df = new DirectoryInfo(strObjPath);

         FileInfo[] fi = (FileInfo[])df.GetFiles("*.txt", SearchOption.TopDirectoryOnly);

         HttpWebClient hwc = new HttpWebClient();       

         for (int i = 0; i < fi.Length; i++)

         {

             if (fi[i].FullName.Length > 12 && fi[i].FullName.Substring(fi[i].FullName.Length - 12) == "_Control.txt")

             {               

                 if (hwc.JudgeControlFileIfFinished(fi[i].FullName) == true)

                 {

                     hwc.DeleteControlFile(fi[i].FullName);

                     KillAllThreads();

                     return true;

                 }

             }

         }

         return false;

     }

 

     private void KillAllThreads()

     {

         foreach (Thread t in HttpWebClient.threads)

         {

             if (t.IsAlive)

             {

                 t.Abort();

             }

         }

         HttpWebClient.threads.Clear();

     }

 

 }

 

 

 

 

(四).示例代码下载

       http://www.cnblogs.com/Files/MVP33650/MultiThreadDownLoadFile.rar

(五).Asp.net 2.0其它相关文章:     

           http://blog.csdn.net/ChengKing/category/288694.aspx

 

 

http://blog.csdn.net/ChengKing/archive/2007/06/21/1661146.aspx