How do I load a FileResource into a byte array?

I have a file called data.dat that I would like to load into a byte[] in Vaadin. It is a data file that I need to load and then manipulate based on the user's input.

I tried:

String basepath = VaadinService.getCurrent().getBaseDirectory().getAbsolutePath();
FileResource resource = new FileResource(new File(basepath + MY_DATA_FILE));    

The problem is that I don't know how to manipulate the resource to extract the byte[]. I see lots of information for how to put images and so on to the UI components, how to stream a user generated PDF, and so on, but I can't seem to find any examples on how to load your own data file that you then manipulate within code...