@Transactional(isolation=Isolation.REPEATABLE_READ)
class SampleServiceImpl implements SampleService {

@Autowired
private SessionFactory sessionFactory;

@Override
public void request_1() {

    Session session = sessionFactory.openSession();
    Transaction transaction = session.beginTransaction();

    City city = (City) session.get(City.class, 1L);
    System.out.println(city);

    session.clear();

    city = (City) session.get(City.class, 1L);
    System.out.println(city);

    transaction.commit();
    session.close();

}

@Override
public void request_2() {
    Session session = sessionFactory.openSession();
    Transaction transaction = session.beginTransaction();

    City city = (City) session.get(City.class, 1L);
    System.out.println(city);

    city.setName("ShangHai");
    city.setCountry("China");

    session.flush();

    transaction.commit();
    session.close();

}