@Override
public GetBookResult execute(GetBookCommand command) {
validateCommand(command);
Book book = jpacrudOperationDAO.getById(Book.class, command.getBookId());
if (book == null || !book.getBookId().equals(command.getBookId())) {
throw new RuntimeException("Book id not valid");
}
return new GetBookResult(book);
}
private void validateCommand(GetBookCommand command) {
checkNotNull(command, "GetBookCommand must not be null");
checkNotNull(command.getBookId(), "Book id must not be null");
}