Hibernate_Map_Mapping

//Class For Group

@Entity

@Table(name = "t_group")

public class Group {

private int id;//PK

private String name;

private Map<Integer, User> map = new HashMap<Integer, User>();

@OneToMany(mappedBy = "group", cascade = { CascadeType.ALL })

@MapKey(name="id")

public Map<Integer, User> getMap() {

return map;

}

gets/sets methods.....

//Class For User

public class User {

private int id;//PK

private String name;

private Group group;

// 對 User 對象相關聯的對象都自動級聯操做;

@ManyToOne(cascade = { CascadeType.ALL })

gets/sets methods...

//測試:
                // 存;
		User u1 = new User();
		u1.setName("u1_name");
		User u2 = new User();
		u2.setName("u2_name");

		Configuration cfg = new Configuration().configure();
		SessionFactory factory = cfg.buildSessionFactory();
		Session session = factory.getCurrentSession();
		session.beginTransaction();
		session.save(u1);
		session.save(u2);
		session.getTransaction().commit();

		Session session2 = factory.getCurrentSession();
		session2.beginTransaction();

		Group group = new Group();
		group.setName("u_group");
		group.getMap().put(u1.getId(), u1);
		group.getMap().put(u2.getId(), u2);

		u1.setGroup(group);
		u2.setGroup(group);
		session2.save(group);
		session2.getTransaction().commit();

		// 取;
		Session session3 = factory.getCurrentSession();
		session3.beginTransaction();
		Group _g = (Group) session3.load(Group.class, group.getId());

		for (Map.Entry<Integer, User> entry : _g.getMap().entrySet()) {
			System.out.println(entry.getValue().getName());
		}
		session3.getTransaction().commit();