java - How do I load a FileResource into a byte array? -

i have file called data.dat load byte[] in vaadin. data file need load , manipulate based on user's input.

i tried:

string basepath = vaadinservice.getcurrent().getbasedirectory().getabsolutepath(); fileresource resource = new fileresource(new file(basepath + my_data_file));     

the problem don't know how manipulate resource extract byte[]. see lots of information how put images , on ui components, how stream user generated pdf, , on, can't seem find examples on how load own data file manipulate within code...

from docs of vaadin have:

java.io.file    getsourcefile()        gets source file. 

or

downloadstream getstream()      gets resource stream. 

and in downloadstream:

java.io.inputstream getstream()        gets downloadable stream. 

so can operate on file or inputstream read contents of fileresource

for example in java 8:

byte[] bytes = files.readallbytes(paths.get(resource.getsourcefile().getabsolutepath()));