下载附件代码

  Response.Clear();
                Response.ClearContent();
                Response.ClearHeaders();
                Response.ContentType = "application/octet-stream ; Charset=UTF8";
                Response.CacheControl = "public";
               
                string realFileName = fileName.IndexOf('_') > 0 ? fileName.Remove(0, fileName.IndexOf('_') + 1) : fileName;
                Response.AddHeader("Content-Disposition", "attachment;filename=\"" + HttpUtility.UrlEncode(realFileName, System.Text.Encoding.GetEncoding("UTF-8")) + "\"");
                Response.AddHeader("Content-Length", fileSize.ToString());
                Response.AddHeader("Content-Transfer-Encoding", "binary");
                Response.Filter.Close();

 #region
               // int everySize =Convert.ToInt32(System.Configuration.ConfigurationManager.AppSettings["EverySize"].ToString()); //每次读取配置文件中分块下载的大小
               // byte[] buffers=new byte[everySize];
               //// System.IO.FileStream istream = System.IO.File.OpenRead(fileInfo.FullName);
               // using (System.IO.FileStream istream = new FileStream(fileInfo.FullName, FileMode.Open, FileAccess.Read, FileShare.Read))
               // {
               //     long dataLenghtRead = istream.Length;
               //     while (dataLenghtRead > 0 && Response.IsClientConnected)
               //     {
               //         int readLength = istream.Read(buffers, 0, everySize);
               //         Response.OutputStream.Write(buffers, 0, readLength);
               //         Response.Flush();
               //         dataLenghtRead = dataLenghtRead - readLength;
               //     }
               // }
               /////Response.WriteFile(fileInfo.FullName);
               //istream.Close();
               //istream.Dispose();
                #endregion