正在下载文件。网络问题导致文件损坏

HttpWebRequest -> WebResponse -> Stream -> FileStream . 参见下面的代码。

1. 开始下载。
2. 拔下电缆或单击以暂停下载过程。
3. 关闭并打开应用程序。
4. 开始下载(从中断点开始)。

问题:下载的文件已损坏。

public class Downloader
{
    int StartPosition { get; set; }
    int EndPosition { get; set; }
    bool Cancelling { get; set; }

    void Download(string[] args)
    {
        string uri = @"http://www.example.com/hugefile.zip";
        string localFile = @"c:\hugefile.zip";
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
        request.AddRange(this.StartPosition);
        WebResponse response = request.GetResponse();
        Stream inputStream = response.GetResponseStream();

        using (FileStream fileStream = new FileStream(localFile, FileMode.Open, FileAccess.Write))
        {
            int buffSize = 8192;
            byte[] buffer = new byte[buffSize];
            int readSize;

            do
            {
                // reads the buffer from input stream
                readSize = inputStream.Read(buffer, 0, buffSize);

                fileStream.Position = this.StartPosition;
                fileStream.Write(buffer, 0, (int)readSize);
                fileStream.Flush();

                // increase the start position
                this.StartPosition += readSize;

                // check if the stream has reached its end
                if (this.EndPosition > 0 && this.StartPosition >= this.EndPosition)
                {
                    this.StartPosition = this.EndPosition;
                    break;
                }

                // check if the user have requested to pause the download
                if (this.Cancelling)
                {
                    break;
                }
            }
            while (readSize > 0);
        }
    }
}