hibernate many-to-one疑惑

[code="java"]
User user = (User)session.get(User.class, 3);
System.out.println("user.name=" + user.getName());
System.out.println("user.group.name=" + user.getGroup().getName());
[/code]

为什么在执行get时，只发出一条查询user的语句，
System.out.println("user.group.name=" + user.getGroup().getName());
这里才查询group

控制台:
Hibernate: select user0_.id as id0_0_, user0_.name as name0_0_, user0_.groupid as groupid0_0_ from t_user user0_ where user0_.id=?
user.name=菜
Hibernate: select group0_.id as id1_0_, group0_.name as name1_0_ from t_group group0_ where group0_.id=?
user.group.name=vip

这个就是延迟加载，你可以在节点<many-to-one 上加入fetch="join" lazy="false" 使其在查用户时就查出group

join select 这是抓取fetch两个策略,默认应该是select也就是你不操作它时,它不会马上加载对象,当你访问group.name就发一条执行,
如果你设置了join,就是使用连接查询了,select * from XXX left join XXA.xxxxxxxxxxx