Java持久化API概述及使用

// 'em' is an EntityManager instance
em.getTransaction().begin();
// use a hard-coded player id for convenience in this sample only
Player player = em.find(Player.class, 5L);
if (player != null) ...{
    System.out.println(player.toString());
    em.remove(player);
}
em.getTransaction().commit();