UserServiceImpl.java

@Service
public class UserServiceImpl implements UserService {

  @Autowired
  private UserDao userDao;

  @Override
  @Transactional(readOnly = true)
  public ServerResponse getUser(Long userId) {
    ServerResponse response = new ServerResponse();

    UserDTO dto = userDao.getUser(userId);
    response.setUser(new User(dto.getFirstName() + " " + dto.getLastName(), 
                        new Long(dto.getAge())));

    return response;
  }

}