小记,提供文件下载,并控制下载速度

              /// <summary>

              /// 输出硬盘文件,提供下载

              /// </summary>     

              /// <param name="context">HttpContext对象</param>

              /// <param name="_fullPath">要下载的文件的完整路径</param>

              /// <param name="_speed">每秒允许下载的字节数</param>

              /// <returns>是否成功</returns>

              public static bool ResponseFile(HttpContext context,string _fullPath, long _speed)

              {

                     HttpRequest _Request = context.Request;

                     HttpResponse _Response = context.Response;

                     string strFileName = new FileInfo(_fullPath).Name;

                     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       进行拆包,每包大小

                                   int sleep = (int)Math.Floor(1000 * pack / _speed) + 1;       //pack/_speed 每个包发送速度/ 总的意思:发包频率

                                   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=" + HttpUtility.UrlEncode(strFileName,System.Text.Encoding.UTF8) );

 

                                   br.BaseStream.Seek(startBytes, SeekOrigin.Begin);

                                   int maxCount = (int) Math.Floor((fileLength - startBytes) / pack) + 1;

 

                                   for (int i = 0; i < maxCount; i++)

                                   {

                                          if (_Response.IsClientConnected)

                                          {

                                                 _Response.BinaryWrite(br.ReadBytes(pack));

                                                 _Response.Flush();

                                                 System.Threading.Thread.Sleep(sleep);              //线程休息sleep毫秒后继续

                                          }

                                          else

                                          {

                                                 i=maxCount;

                                          }

                                   }

                            }

                            catch

                            {

                                   return false;

                            }

                            finally

                            {

                                   br.Close();

                                   myFile.Close();

                            }

                     }

                     catch

                     {

                            return false;

                     }

                     return true;

              }

 

posted on 2006-10-26 17:24  房客  阅读(706)  评论(0编辑  收藏  举报

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