断点续传

// 这是断点续传的下载进度我想应该可以得到已经下载的文件大小!  
   public     static     bool    ResponseFile(   System.Web.HttpRequest   _Request,  
                        System.Web.HttpResponse   _Response,  
                         string    _fileName, string    _fullPath,    long    _speed)  
       {  
        try  
        {  
          FileStream   myFile   =   new   FileStream(_fullPath,   FileMode.Open,   FileAccess.Read,   FileShare.ReadWrite);  
          BinaryReader   br   =   new   BinaryReader(myFile);  
          try  
          {  
            _Response.AddHeader("Accept-Ranges",   "bytes");  
            _Response.Buffer   =   false;  
            long   fileLength   =   myFile.Length;  
            long   startBytes   =   0;  
             
            int   pack   =   10240;   //10K   bytes  
            if   (_Request.Headers["Range"]   !=   null)  
            {  
              _Response.StatusCode   =   206;  
              string[]   range   =   _Request.Headers["Range"].Split(new   char[]   {'=',   '-'});  
              startBytes   =   Convert.ToInt64(range[1]);  
            }  
            _Response.AddHeader("Content-Length",   (fileLength   -   startBytes).ToString());  
            if   (startBytes   !=   0)  
            {  
              _Response.AddHeader("Content-Range",   string.Format("   bytes   {0}-{1}/{2}",   startBytes,   fileLength-1,   fileLength));  
            }  
            _Response.AddHeader("Connection",   "Keep-Alive");  
            _Response.ContentType   =   "application/octet-stream";  
            _Response.AddHeader("Content-Disposition","attachment;filename="   +   System.Web.HttpUtility.UrlEncode(_fileName,System.Text.Encoding.UTF8)   );  
             
            br.BaseStream.Seek(startBytes,   SeekOrigin.Begin);  
            int   maxCount   =   (int)   Math.Floor((fileLength   -   startBytes)   /   pack)   +   1;  
            byte[]   buffer=new   byte[pack];  

            for   (int   i   =   0;   i   <   maxCount;   i++)  
            {  
              if   (_Response.IsClientConnected)  
              {  
                buffer=br.ReadBytes(pack);  
                _Response.OutputStream.Write(buffer,   0,   pack);  
                _Response.Flush();  
                buffer=new   byte[pack];  

              }  
              else  
              {  
                i=maxCount;    
              }  
            }  
          }  
          catch(Exception   myerror)    
          {  
            throw   myerror;  
          }  
          finally  
          {  
            br.Close();  
            myFile.Close();  
          }  
        }  
        catch(Exception   myerror)  
        {  
          throw   myerror;    
        }  
        return   true;  
      }