code: public static byte[] fileHash(File file, MessageDigest messageDigest)
              throws IOException {
          return computeHash(file, messageDigest, 0L, file.length());
      }
docs: Returns the hash value of the file for the specified messageDigest.
  
  @param file
  to compute the hash value for
  @param messageDigest
  the message digest algorithm
  @return hash value of the file
  @throws IOException