Question

我正在使用Google Drive API从Google Drive下载文件，它可以正常工作，但是我想执行更多暂停和恢复功能。

我阅读了Google的说明页，发现支持部分下载（https://developers.google.com/drive/api/v3/manage-downloads），他们说：“您可以使用带有Range头的字节范围来指定要下载的文件部分”，但我不知道该怎么办，谁可以帮助我？

这是我的代码：

string fileId;
string path;
long bytes;
        private void DownloadWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            DriveService ds = GetService();
            var request = ds.Files.Get(fileId);

            using (var stream = new MemoryStream())
            {

                request.MediaDownloader.ProgressChanged += (Google.Apis.Download.IDownloadProgress progress) =>
                {
                    switch (progress.Status)
                    {
                        case Google.Apis.Download.DownloadStatus.Downloading:
                            {
                                bytes = progress.BytesDownloaded;
                                GoogleDrive.ReportProgress((int)bytes);
                                break;
                            }
                        case Google.Apis.Download.DownloadStatus.Completed:
                            {
                                SaveStream(stream);
                                break;
                            }
                        case Google.Apis.Download.DownloadStatus.Failed:
                            {
                                break;
                            }
                    }
                };
                request.Download(stream);

            }
        }
        private void DownloadWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text = e.ProgressPercentage.ToString();
        }
        private void DownloadWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {

        }
        private void SaveStream(MemoryStream stream)
        {
            long exlength = 0;
            if (System.IO.File.Exists(path))
            {
                var fileInfo = new FileInfo(path);
                exlength = fileInfo.Length;
            }
            var fileMode = exlength > 0 ? FileMode.Append : FileMode.Create;
            using (FileStream file = new FileStream(path, fileMode, FileAccess.Write))
            {
                stream.WriteTo(file);
            }
        }

        private void Button1_Click(object sender, EventArgs e)
        {
            fileId = "1P2KckTacknNDsONttlzL4GPLSLldzCbA";
            path = "D:\\Data.zip";
            GoogleDrive.RunWorkerAsync();

        }

Answer 1

已经有一个与您要在此处实现的结果类似的答案[1]，但有一个导出请求。基本上，在收到请求之后（发送之前），您需要按照发布的链接中所述设置Range标头。对于您的情况，将是这样的：

DriveService ds = GetService(); 
var request = ds.Files.Get(fileId);
//Set the range header
request.Headers.Range = new RangeHeaderValue(from, to);
//More code…
//Send the request
request.Download(stream);

[1] C# - Downloading from Google Drive in byte chunks

可恢复下载的Google Drive API

1 个答案: