How do I read a binary file in a Windows Store app

问题:

How can I read a binary file in a Windows Store app, or more specifically how can I create my Stream, when the System.IO namespace contains no File class?

The documentation examples for BinaryReader unhelpfully use File!

回答1:

You always access files in Windows Store apps using StorageFile class:

StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(filename);

You can then get the binary contents of the file using the WinRT APIs:

IBuffer buffer = await FileIO.ReadBufferAsync(file);
byte[] bytes = buffer.ToArray();

If you want to use BinaryReader you need a stream instead:

StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync("a");
Stream stream = (await file.OpenReadAsync()).AsStreamForRead();
BinaryReader reader = new BinaryReader(stream);

Make sure you only use ReadBytes() for binary data in this case which doesn't take encoding into account.