App8.java 文件源码

public static void main(String[] args) {
    EntityManagerFactory entityManagerFactory = Persistence
            .createEntityManagerFactory("pl.edu.bogdan.training.db.entity");
    EntityManager em = entityManagerFactory.createEntityManager();

    em.getTransaction().begin();

    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<User> cq = cb.createQuery(User.class);
    Root<User> from = cq.from(User.class);
    Join<User, Role> join = from.join("role", JoinType.LEFT);
    cq.where(cb.equal(join.get("name"), "ordinary"));
    TypedQuery<User> tq = em.createQuery(cq);
    List<User> users = tq.getResultList();
    for (User u : users) {
        System.out.println(u.getLastName());
    }

    em.getTransaction().commit();
    em.close();
    entityManagerFactory.close();
}