服务器下载文件http

    #region 从服务器下载文件
    /// <summary>
    /// 从服务器下载文件
    /// </summary>
    /// <param name="_Request"></param>
    /// <param name="_Response"></param>
    /// <param name="_fileName">文件名称</param>
    /// <param name="_fullPath">文件完整路径</param>
    /// <param name="_speed">速度</param>
    /// <returns></returns>
    public bool ResponseFile(HttpRequest _Request, 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
                //int sleep = 200;   //每秒5次   即5*10K bytes每秒
                int sleep = (int)Math.Floor((decimal)1000 * pack / _speed) + 1;
                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.Charset = "UTF-8";
                _Response.ContentEncoding = Encoding.GetEncoding("UTF-8");
                _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(_fileName, System.Text.Encoding.UTF8));

                br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
                int maxCount = (int)Math.Floor((decimal)(fileLength - startBytes) / pack) + 1;

                for (int i = 0; i < maxCount; i++)
                {
                    if (_Response.IsClientConnected)
                    {
                        _Response.BinaryWrite(br.ReadBytes(pack));
                        Thread.Sleep(sleep);
                    }
                    else
                    {
                        i = maxCount;
                    }
                }
                _Response.End();

            }
            catch
            {
                return false;
            }
            finally
            {
                br.Close();
                myFile.Close();
                //下载后后删除路径

              /*
                if (File.Exists(_fullPath))
                {
                    File.Delete(_fullPath);
                }

              */
            }
        }
        catch
        {
            return false;
        }

        return true;

    }
    #endregion