通用 Windows 平台 ZipFile.CreateFromDirectory 创建空 ZIP 文件

Question

I have a problem with zipping existing directories. When I try to compress an existing directory, I always get an empty zip file. My code is based on this example from MSDN . There are no exceptions when debugging the application.

My code:

private async void PickFolderToCompressButton_Click(object sender, RoutedEventArgs e)
{
    // Clear previous returned folder name, if it exists, between iterations of this scenario
    OutputTextBlock.Text = "";

    FolderPicker folderPicker = new FolderPicker();
    folderPicker.SuggestedStartLocation = PickerLocationId.Desktop;
    folderPicker.FileTypeFilter.Add(".dll");
    folderPicker.FileTypeFilter.Add(".json");
    folderPicker.FileTypeFilter.Add(".xml");
    folderPicker.FileTypeFilter.Add(".pdb");
    StorageFolder folder = await folderPicker.PickSingleFolderAsync();
    if (folder != null)
    {
        // Application now has read/write access to all contents in the picked folder (including other sub-folder contents)
        StorageApplicationPermissions.FutureAccessList.AddOrReplace("PickedFolderToken", folder);
        OutputTextBlock.Text = $"Picked folder: {folder.Name}";

        var files  = await folder.GetFilesAsync();
        foreach (var file in files)
        {
            OutputTextBlock.Text += $"\n {file.Name}";
        }

        await Task.Run(() =>
        {
            try
            {
                ZipFile.CreateFromDirectory(folder.Path, $"{folder.Path}\\{Guid.NewGuid()}.zip",
                    CompressionLevel.NoCompression, true);
                Debug.WriteLine("folder zipped");
            }
            catch (Exception w)
            {
                Debug.WriteLine(w);
            }
        });
    }
    else
    {
        OutputTextBlock.Text = "Operation cancelled.";
    }
}

A Zip file is created, but it is always empty. There are many files in the source folder.

Answer 1

We found this could be caused by the implementation of the .NET Core for the filesystem api.

Current workaround is to firstly put your folder to be zipped to the local data folder of the windows runtime app, and read from this folder could generate an expected result when using the zipfile class.

You can refer to a related post on MSDN.

Answer 2

The zipfile library only supports zipping back to application localfolder. If you have the permission token from other folder, you might want to zip directly. The writeZip function can also be used to add a separate file from elsewhere.

        public async void Backup(StorageFolder source, StorageFolder destination)
        {
            var zipFile = await destination.CreateFileAsync("backup.zip",
               CreationCollisionOption.ReplaceExisting);

            var zipToCreate = await zipFile.OpenStreamForWriteAsync();
            using (var archive = new ZipArchive(zipToCreate, ZipArchiveMode.Update))
            {
                var parent = source.Path.Replace(source.Name, "");
                await RecursiveZip(source, archive, parent);
            }
        }

        private async Task RecursiveZip(StorageFolder sourceFolder, ZipArchive archive, string sourceFolderPath)
        {
            var files = await sourceFolder.GetFilesAsync();
            foreach (var file in files)
            {
                await WriteZip(file, archive, sourceFolderPath);
            }

            var subFolders = await sourceFolder.GetFoldersAsync();
            foreach (var subfolder in subFolders)
            {
                await RecursiveZip(subfolder, archive, sourceFolderPath);
            }
        }

        private async Task WriteZip(StorageFile file, ZipArchive archive, string sourceFolderPath)
        {
            var entryName = file.Path.Replace(sourceFolderPath, "");
            var readmeEntry = archive.CreateEntry(entryName, CompressionLevel.Optimal);
            var reader = await file.OpenStreamForReadAsync();
            using (var entryStream = readmeEntry.Open())
            {
                await reader.CopyToAsync(entryStream);
            }
        }