ASP.NET 后台下载文件方法

 void DownLoadFile(string fileName)
     {
         string filePath = Server.MapPath(fileName);//路径

         //以字符流的形式下载文件
         FileStream fs = new FileStream(filePath, FileMode.Open);
         byte[] bytes = new byte[(int)fs.Length];
         fs.Read(bytes, , bytes.Length);
         fs.Close();
         Response.ContentType = "application/octet-stream";
         //通知浏览器下载文件而不是打开
         Response.AddHeader("Content-Disposition", "attachment; filename=" +     HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
         Response.BinaryWrite(bytes);
         Response.Flush();
         Response.End();
     }