list()查询
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//一次性把数据对象取出来
@Test
public
void
findTestList(){
Session s=sessionFactory.getCurrentSession();
s.beginTransaction();
List<Person> persons=s.createQuery(
"from Person"
).list();
for
(Person person:persons){
System.out.println(person.getName()+
"----"
+person.getId());
}
s.getTransaction().commit();
}
|
sql语句如下:
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16:00:43,118 DEBUG SQL:111 -
select
person0_.id
as
id1_,
person0_.p_age
as
p2_1_,
person0_.group_id
as
group4_1_,
person0_.p_name
as
p3_1_
from
p_person person0_
张三0
----1
张三1
----2
张三2
----3
张三3
----4
张三4
----5
张三5
----6
张三6
----7
张三7
----8
张三8
----9
张三9
----10
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iterate()查询
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//一次性取出来的是所有对象的主键值，并且会把这些主键值放在Session缓冲中去
//下次需要的话，直接在Session中获取，不需要再次访问数据库
//缺点是将查询出来的主键值，分别再以主键进行取值对象，造成数据库压力巨大
@Test
public
void
findTestIterate(){
Session s=sessionFactory.getCurrentSession();
s.beginTransaction();
Iterator<Person> persons=s.createQuery(
"from Person"
).iterate();
while
(persons.hasNext()){
System.out.println(persons.next().getName());
}
s.getTransaction().commit();
}
|
sql语句
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16:03:55,776 DEBUG SQL:111 -
select
person0_.id
as
col_0_0_
from
p_person person0_
16:03:55,806 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三0
16:03:55,823 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三1
16:03:55,826 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三2
16:03:55,832 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三3
16:03:55,836 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三4
16:03:55,838 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三5
16:03:55,841 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三6
16:03:55,844 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三7
16:03:55,846 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三8
16:03:55,875 DEBUG SQL:111 -
select
person0_.id
as
id1_0_,
person0_.p_age
as
p2_1_0_,
person0_.group_id
as
group4_1_0_,
person0_.p_name
as
p3_1_0_
from
p_person person0_
where
person0_.id=?
张三9
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get()查询
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//立刻发送sql语句，不管我们是否需要，比如person.getName();
@Test
public
void
findTestget(){
Session s=sessionFactory.getCurrentSession();
s.beginTransaction();
Person person=(Person)s.get(Person.
class
,
1
);
// System.out.println(person.getName());
s.getTransaction().commit();
}
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load()查询
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//不会立刻发送sql语句，只有当我们需要的时候才会发送sql语句，比如person.getName();
@Test
public
void
findTestload(){
Session s=sessionFactory.getCurrentSession();
s.beginTransaction();
Person person=(Person)s.load(Person.
class
,
1
);
// System.out.println(person.getName());
s.getTransaction().commit();
}
|
本文转自 小夜的传说 51CTO博客，原文链接：http://blog.51cto.com/1936625305/1576128，如需转载请自行联系原作者
