one-to-one双向关联之加载 - 数据库编程

4-02-04 17:07:40 INFO org.hibernate.tool.hbm2ddl.TableMetadata:67 - HHH000037: Columns: [id, husband_id, name]
2014-02-04 17:07:40 INFO org.hibernate.tool.hbm2ddl.TableMetadata:69 - HHH000108: Foreign keys: [fk_fi3kodkmubgryyblf4935y4dk]
2014-02-04 17:07:40 INFO org.hibernate.tool.hbm2ddl.TableMetadata:70 - HHH000126: Indexes: [pk__t_wife__3213e83f1332dbdc]
2014-02-04 17:07:40 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:242 - HHH000232: Schema update complete
Hibernate:
select
husband0_.id as id1_0_0_,
husband0_.name as name2_0_0_,
wife1_.id as id1_1_1_,
wife1_.husband_id as husband_3_1_1_,
wife1_.name as name2_1_1_
from
t_husband husband0_
left outer join
t_wife wife1_
on husband0_.id=wife1_.husband_id
where
husband0_.id=
*****************
Hibernate:
select
wife0_.id as id1_1_0_,
wife0_.husband_id as husband_3_1_0_,
wife0_.name as name2_1_0_
from
t_wife wife0_
where
wife0_.id=

这样wife类只加载自己主表的信息，不考虑从表的信息了( 当然把husband也是如此，可以自己去试试)。

hibernate默认的加载策略为eager加载，也就是急抓取，会把所关联的信息一次性全部得到，而lazy则都是在你用到从表才会去加载。

我们改变一下测试类内容：

	public void One_to_oneLoadTest1() {
		// 一对一双向关联

		Session s = sessionFacotry.getCurrentSession();

		s.beginTransaction();

		Husband hus = (Husband) s.get(Husband.class, 2);

    	

		System.out.println("*****************");
		Wife wif = (Wife) s.get(Wife.class, 3);
		

		System.out.println(wif.getHusband().getName());
		s.getTransaction().commit();

	}

输出如下：

2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:182 - HHH000228: Running hbm2ddl schema update
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:193 - HHH000102: Fetching database metadata
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:205 - HHH000396: Updating schema
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:66 - HHH000261: Table found: hibernate.dbo.t_husband
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:67 - HHH000037: Columns: [id, name]
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:69 - HHH000108: Foreign keys: []
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:70 - HHH000126: Indexes: [pk__t_husban__3213e83f0f624af8]
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:66 - HHH000261: Table found: hibernate.dbo.t_wife
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:67 - HHH000037: Columns: [id, husband_id, name]
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:69 - HHH000108: Foreign keys: [fk_fi3kodkmubgryyblf4935y4dk]
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.TableMetadata:70 - HHH000126: Indexes: [pk__t_wife__3213e83f1332dbdc]
2014-02-04 17:10:51 INFO org.hibernate.tool.hbm2ddl.SchemaUpdate:242 - HHH000232: Schema update complete
Hibernate:
select
husband0_.id as id1_0_0_,
husband0_.name as name2_0_0_,
wife1_.id as id1_1_1_,
wife1_.husband_id as husband_3_1_1_,
wife1_.name as name2_1_1_
from
t_husband husband0_
left outer join
t_wife wife1_
on husband0_.id=wife1_.husband_id
where
husband0_.id=
*****************
Hibernate:
select
wife0_.id as id1_1_0_,
wife0_.husband_id as husband_3_1_0_,
wife0_.name as name2_1_0_
from
t_wife wife0_
where
wife0_.id=
Hibernate:
select
husband0_.id as id1_0_0_,
husband0_.name as name2_0_0

one-to-one双向关联之加载(四)