import org.hibernate.LockMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;

public class Hiber {


  public static void main(String[] args) {
    Configuration config = new Configuration();

    config.addAnnotatedClass(A.class);
    config.addAnnotatedClass(B.class);

    config.setProperty("hibernate.connection.driver_class", "org.postgresql.Driver");
    config.setProperty("hibernate.connection.url", "jdbc:postgresql://localhost/heymoose");
    config.setProperty("hibernate.connection.username", "postgres");
    config.setProperty("hibernate.connection.password", "");
    config.setProperty("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
    config.setProperty("hibernate.hbm2ddl.auto", "create-drop");
    config.setProperty("hibernate.show_sql", "true");
    config.setProperty("hibernate.format_sql", "false");
    config.setProperty("hibernate.transaction.factory_class", "org.hibernate.transaction.JDBCTransactionFactory");
    config.setProperty("hibernate.current_session_context_class", "thread");
    config.setProperty("hibernate.jdbc.batch_size", "0");

    SessionFactory sessionFactory = config.buildSessionFactory();

    Integer id;

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

    A a = new A();
    B b = new B();
    b.setName("foo");
    a.setB(b);
    session.save(a);
    id = a.getId();

    session.getTransaction().commit();
    session.close();

    session = sessionFactory.openSession();
    session.beginTransaction();

    a = (A) session.get(A.class, id);
    b = a.getB();
    int bid = b.getId();
    session.evict(b);
    session.lock(b, LockMode.UPGRADE);
    b = (B) session.createCriteria(B.class).add(Restrictions.eq("id", bid)).list().get(0);
    b.setName("bar");

    sessionFactory.getCurrentSession();

    session.getTransaction().commit();
    session.close();
  }
}