Asp.net(c#)实现多线程断点续传

     System.IO.Stream iStream = null;
  
   // Buffer to read 10K bytes in chunk:
   byte[] buffer = new Byte[10240];
  
   // Length of the file:
   int length;
  
   // Total bytes to read:
   long dataToRead;
  
   // Identify the file to download including its path.
   string filepath = @”E:\software\SQL Server 2000 Personal Edition.ISO”;
  
   // Identify the file name.
   string filename = System.IO.Path.GetFileName(filepath);
  
   try
   {
   // Open the file.
   iStream = new System.IO.FileStream(filepath, System.IO.FileMode.Open,
   System.IO.FileAccess.Read,System.IO.FileShare.Read);
   Response.Clear();
  
   // Total bytes to read:
   dataToRead = iStream.Length;
  
   long p = 0;
   if(Request.Headers["Range"]!=null)
   {
   Response.StatusCode = 206;
   p = long.Parse( Request.Headers["Range"].Replace(”bytes=”,”").Replace(”-”,”"));
   }
   if(p != 0)
   {
   Response.AddHeader(”Content-Range”,”bytes ” + p.ToString() + “-” + ((long)(dataToRead - 1)).ToString() + “/” + dataToRead.ToString());
   }
   Response.AddHeader(”Content-Length”,((long)(dataToRead-p)).ToString());
   Response.ContentType = “application/octet-stream”;
   Response.AddHeader(”Content-Disposition”, “attachment; filename=” + System.Web.HttpUtility.UrlEncode(Request.ContentEncoding.GetBytes(filename)));
  
   iStream.Position = p;
   dataToRead = dataToRead - p;
   // Read the bytes.
   while (dataToRead > 0)
   {
   // Verify that the client is connected.
   if (Response.IsClientConnected)
   {
   // Read the data in buffer.
   length = iStream.Read(buffer, 0, 10240);
  
   // Write the data to the current output stream.
   Response.OutputStream.Write(buffer, 0, length);
  
   // Flush the data to the HTML output.
   Response.Flush();
  
   buffer= new Byte[10240];
   dataToRead = dataToRead - length;
   }
   else
   {
   //prevent infinite loop if user disconnects
   dataToRead = -1;
   }
   }
   }
   catch (Exception ex)
   {
   // Trap the error, if any.
   Response.Write(”Error : ” + ex.Message);
   }
   finally
   {
   if (iStream != null)
   {
   //Close the file.
   iStream.Close();
   }
   Response.End();
   }