.net从服务端下载文件

public void DownFile(string guid) ???????{ ???????????var fileTransfer = new FileTransfer(); ???????????var directoryPath = Path.Combine(InitInfo.Config_GarbagePath, "FileImport", guid); ???????????fileTransfer.ChunkTransfer(System.Web.HttpContext.Current, GetDownFilePath(directoryPath)); ???????????HttpContext.Response.Flush(); ???????????//删除临时文件 ???????????// ??Utility.DeleteDirectory(directoryPath); ???????}

 public bool ChunkTransfer(HttpContext httpContext, string filePathName) ???????{ ???????????bool result = false; ???????????if (!System.IO.File.Exists(filePathName)) ???????????{ ???????????????httpContext.Response.StatusCode = 404; ???????????????return false; ???????????} ???????????long startPostion = 0; ???????????long endPostion = 0; ???????????string fileName = Path.GetFileName(filePathName); ???????????using (FileStream fileStream = new FileStream(filePathName, FileMode.Open, FileAccess.Read, FileShare.Read)) ???????????{ ???????????????using (BinaryReader br = new BinaryReader(fileStream)) ???????????????{ ???????????????????long fileLength = fileStream.Length; ???????????????????string lastUpdateTime = System.IO.File.GetLastWriteTimeUtc(filePathName).ToString("r"); ???????????????????string eTag = HttpUtility.UrlEncode(fileName, Encoding.UTF8) + lastUpdateTime;//恢复下载时提取请求头; ????????????????????if (httpContext.Request.Headers["If-Range"] != null) ????????????????????{ ???????????????????????if (httpContext.Request.Headers["If-Range"].Replace("\"", "") != eTag) ???????????????????????{//文件修改过 ?????????????????????????????httpContext.Response.StatusCode = 412;//预处理失败 ?????????????????????????????return false; ???????????????????????} ???????????????????} ???????????????????httpContext.Response.Clear(); ???????????????????httpContext.Response.Buffer = false; ???????????????????httpContext.Response.AddHeader("Accept-Ranges", "bytes"); ???????????????????httpContext.Response.AppendHeader("ETag", "\"" + eTag + "\""); ???????????????????httpContext.Response.AppendHeader("Last-Modified", lastUpdateTime);//把最后修改日期写入响应 ?????????????????????????????????????httpContext.Response.ContentType = "application/octet-stream"; ???????????????????if (httpContext.Request.UserAgent.IndexOf("MSIE") > -1 || (httpContext.Request.UserAgent.IndexOf("like Gecko") > -1)) ???????????????????{ ???????????????????????fileName = HttpUtility.UrlEncode(fileName, Encoding.UTF8).Replace("+", "%20"); ???????????????????} ???????????????????if (httpContext.Request.UserAgent.ToLower().IndexOf("firefox") > -1) ???????????????????{ ???????????????????????httpContext.Response.AddHeader("Content-Disposition", "attachment;filename=\"" + fileName + "\""); ???????????????????} ???????????????????else ???????????????????{ ???????????????????????httpContext.Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName); ???????????????????} ???????????????????httpContext.Response.AddHeader("Connection", "Keep-Alive"); ???????????????????httpContext.Response.ContentEncoding = Encoding.UTF8; ???????????????????if (httpContext.Request.Headers["Range"] != null)//续传 ???????????????????{ ???????????????????????httpContext.Response.StatusCode = 206;//续传标识 ???????????????????????string[] range = httpContext.Request.Headers["Range"].Split(new char[] { ‘=‘, ‘-‘ }); ???????????????????????startPostion = long.Parse(range[1]);//已经下载的字节数 ???????????????????????if (startPostion < 0 || startPostion >= fileLength) ???????????????????????{ ???????????????????????????return false; ???????????????????????} ???????????????????????if (string.IsNullOrEmpty(range[2]))//只指定请求文件起始 ???????????????????????{ ???????????????????????????httpContext.Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startPostion, fileLength - 1, fileLength)); ???????????????????????????httpContext.Response.AddHeader("Content-Length", (fileLength - startPostion).ToString()); ???????????????????????} ???????????????????????else//指定请求文件范围 ???????????????????????{ ???????????????????????????endPostion = long.Parse(range[2]); ???????????????????????????httpContext.Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startPostion, endPostion - startPostion - 1, fileLength)); ???????????????????????????httpContext.Response.AddHeader("Content-Length", (endPostion - startPostion).ToString()); ???????????????????????} ???????????????????} ???????????????????else ???????????????????{//非续传 ???????????????????????httpContext.Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startPostion, fileLength - 1, fileLength)); ???????????????????????httpContext.Response.AddHeader("Content-Length", (fileLength - startPostion).ToString()); ???????????????????} ???????????????????br.BaseStream.Seek(startPostion, SeekOrigin.Begin); ???????????????????long maxCount = (long)Math.Ceiling((fileLength - startPostion + 0.0) / TransferBuffer);//分块下载，剩余部分可分成的块数 ?????????????????????for (long i = 0; i < maxCount && httpContext.Response.IsClientConnected; i++) ???????????????????{ ???????????????????????httpContext.Response.BinaryWrite(br.ReadBytes(TransferBuffer)); ???????????????????????httpContext.Response.Flush(); ???????????????????????if (TransferSleep > 0) ???????????????????????{ ???????????????????????????Thread.Sleep(TransferSleep); ???????????????????????} ???????????????????} ???????????????????result = true; ???????????????} ???????????} ???????????return result; ???????}