Exception on Extracting the Zip file in C#

问题

I am working on Extraction Code to Extract Zip file, Using C# in winrt.

I am getting File from Local Drive here:

StorageFile file = await KnownFolders.PicturesLibrary.GetFileAsync("dostoyevsky-poor-folk.zip");
        Stream zipMemoryStream = await file.OpenStreamForReadAsync();
        var folder = ApplicationData.Current.LocalFolder;
        // Create zip archive to access compressed files in memory stream
        using (ZipArchive zipArchive = new ZipArchive(zipMemoryStream, ZipArchiveMode.Read))
        {
            // For each compressed file...
            foreach (ZipArchiveEntry entry in zipArchive.Entries)
            {
                if (entry.Name == "")
                {
                    // Folder
                    await CreateRecursiveFolder(folder, entry);
                }
                else
                {
                    // File
                    await ExtractFile(folder, entry);
                }
            }
        }

I am Extracting For folder here:

private async Task CreateRecursiveFolder(StorageFolder folder, ZipArchiveEntry entry)
{
    var steps = entry.FullName.Split('/').ToList();

    steps.RemoveAt(steps.Count() - 1);

    foreach (var i in steps)
    {
        await folder.CreateFolderAsync(i, CreationCollisionOption.OpenIfExists);

        folder = await folder.GetFolderAsync(i);
    }
}

I am Extracting For File Here:

private async Task ExtractFile(StorageFolder folder, ZipArchiveEntry entry)
        {
        var steps = entry.FullName.Split('/').ToList();
        steps.RemoveAt(steps.Count() - 1);
        foreach (var i in steps)
        {
            folder = await folder.GetFolderAsync(i);
        }
        using (Stream fileData = entry.Open())
        {
            StorageFile outputFile = await folder.CreateFileAsync(entry.Name, CreationCollisionOption.ReplaceExisting);

            using (Stream outputFileStream = await outputFile.OpenStreamForWriteAsync())
            {
                await fileData.CopyToAsync(outputFileStream);
                await outputFileStream.FlushAsync();
            }
        }
    }

When I try to use this I get this exception: 'System.NullReferenceException' . The Exception getting line is the Last line of await outputFileStream.FlushAsync();

Some times I am getting same exception when I try to pick file from Local Drive. Before Getting Exception the Debugger value of await outputFileStream.FlushAsync() looking like this.

Can you Help me out for this.

Thanks

回答1:

Finally, It is Worked for me. Why because I am getting Null value while extraction Because of the package where I am going to extract files. I am sure this is the perfect solution to Extract Zip file for windows store apps using c#. Thanks

来源：https://stackoverflow.com/questions/17215679/exception-on-extracting-the-zip-file-in-c-sharp

标签

microsoft-metro

zip

windows-store-apps

extract