asp.net下载网络文件

private bool DownLoadFile()
    {
        //文件路径 和  文件名称
        string filePath = Server.MapPath("~/DownLoad/myFiles");
        string downLoadFile = "test.mkv";

        FileInfo fileName = new FileInfo(filePath + "\\" + downLoadFile);
        FileStream fileStream = new FileStream(filePath + "\\" + downLoadFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

        //流读取
        BinaryReader binaryReader = new BinaryReader(fileStream);

        //如果文件存在
        if (fileName.Exists)
        {
            try
            {
                long startBytes = 0;
                string lastUpdateTimeStamp = File.GetLastWriteTimeUtc(filePath).ToString("r");
                string encodeData = HttpUtility.UrlEncode(downLoadFile, Encoding.UTF8) + lastUpdateTimeStamp;

                //清除response的内容
                Response.Clear();
                Response.Buffer = false;
                Response.AddHeader("Accept-Ranges", "bytes");
                Response.AppendHeader("ETag", "\"" + encodeData + "\"");
                Response.AppendHeader("Last-Modified", lastUpdateTimeStamp);

                //设置contenttype
                Response.ContentType = "application/octet-stream";

                //在弹出的对话框中，添加上文件名称和文件大小
                Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName.Name);

                Response.AddHeader("Content-Length", (fileName.Length - startBytes).ToString());
                Response.AddHeader("Connection", "Keep-Alive");

                //设置编码格式
                Response.ContentEncoding = Encoding.UTF8;

                //发送数据
                binaryReader.BaseStream.Seek(startBytes, SeekOrigin.Begin);

                //切割数据，以1024字节为一个包
                int maxCount = (int)Math.Ceiling((fileName.Length - startBytes + 0.0) / 1024);

                //以1024为单位，下载数据
                int i;
                for (i = 0; i < maxCount && Response.IsClientConnected; i++)
                {
                    Response.BinaryWrite(binaryReader.ReadBytes(1024));
                    Response.Flush();
                }

                //将当前的下载与总文件大小对比，看看是否下载完毕
                if (i < maxCount) return false;
                return true;
            }
            catch
            {
                return false;
            }
            finally
            {
                //文件流以及流读取关闭
                Response.End();
                binaryReader.Close();
                fileStream.Close();
            }
        }
        else
        {
            ScriptManager.RegisterStartupScript(this, GetType(), "文件不存在", "alert('文件不存在！')", true);
        }
        return false;
    }