检查文件是否下载成功的机制

Question

我需要检查文件是否下载成功。我的行动结果返回了CheckedFileStreamResult。但是，OnResultExecutedhandler甚至在文件下载完成之前就已执行。

我在程序中使用以下建议的解决方案：

public class CheckedFileStreamResult : FileStreamResult
    {
        public CheckedFileStreamResult(FileStream stream, string contentType): base(stream, contentType)
        {
            DownloadCompleted = false;
        }

        public bool DownloadCompleted { get; set; }

        protected override void WriteFile(HttpResponseBase response)
        {
            var outputStream = response.OutputStream;
            response.BufferOutput = false;
            using (FileStream fs = new FileStream("D:\\ABC.pdf", FileMode.Open, FileAccess.Read))
            {
                var buffer = new byte[_bufferSize];
                var count = fs.Read(buffer, 0, _bufferSize);
                while (count != 0 && response.IsClientConnected)
                {
                    outputStream.Write(buffer, 0, count);
                    response.Flush();
                    count = fs.Read(buffer, 0, _bufferSize);
                }
                DownloadCompleted = response.IsClientConnected;
            }
        }
        private const int _bufferSize = 0x200;
    }

使用这种机制无法达到预期的效果。在完全下载文件之前执行OnResultExecuted处理程序，并且DownloadCompleted标志给出错误的印象。请指导我如何进行。