import org.hibernate.Session;
import org.hibernate.Transaction;
import org.hibernate.TransactionException;

// ...

Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = null;

try {
    transaction = session.beginTransaction();

    // 트랜잭션 격리 수준 설정
    transaction.setIsolationLevel(Connection.TRANSACTION_READ_COMMITTED);

    // 작업 수행

    session.getTransaction().commit();
} catch (TransactionException e) {
    if (transaction != null) {
        transaction.rollback();
    }
} finally {
    session.close();
}