Question

What is the best way to read amnd write and IO.Stream (Zip file downloded from internet in my case) to ApplicationData.Current.LocalFolder

I tried

public static async Task WriteToFile(
       this System.IO.Stream input,
       string fileName,
       StorageFolder folder = null)
    {
        folder = folder ?? ApplicationData.Current.LocalFolder;
        var file = await folder.CreateFileAsync(
            fileName,
            CreationCollisionOption.ReplaceExisting);
        using (var fs = await file.OpenAsync(FileAccessMode.ReadWrite))
        {
            using (var outStream = fs.GetOutputStreamAt(0))
            {
                using (var dataWriter = new DataWriter(outStream))
                {
                    byte[] buffer = new byte[8 * 1024];
                    int len;
                    while ((len = input.Read(buffer, 0, buffer.Length)) > 0)
                    {
                        dataWriter.WriteBytes(buffer);
                    }

                    await dataWriter.StoreAsync();
                    dataWriter.DetachStream();
                }

                await outStream.FlushAsync();
            }
        }
    }

for writing and

StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(filename);
var fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read);
var stream = fileStream.AsStreamForRead();

but the file gets corrupted somewhere along the way.I do no think there is a problem with reading so it should be somewhere in writing the file. Is there a better way to write IO.Stream to ApplicationData.Current.LocalFolder that works?

Answer 1

Try this:

static async void DownloadFileAsync(
    this HttpClient httpClient,
    string requestUri,
    string fileName,
    StorageFolder folder = null)
{
    folder = folder ?? ApplicationData.Current.LocalFolder;

    var file = await folder.CreateFileAsync(
        fileName, CreationCollisionOption.ReplaceExisting);

    using (var httpStream = await httpClient.GetStreamAsync(uri))
    using (var fileStream = await file.OpenAsync(FileAccessMode.ReadWrite))
    {
        await httpStream.CopyToAsync(fileStream.AsStreamForWrite());
    }
}

MSDN: Http­Client Class, Http­Client.­Get­Stream­Async Method, Windows­Runtime­Stream­Extensions.­As­Stream­For­Write Method, Stream.­Copy­To­Async Method.