Hibernate-Criteria学习笔记
2024-08-30 09:21:51
hibernate_jpa注解
目前最新版的hibernate,5.2,底层整合了jpa,用idea的hibernate工具生成实体时,实体包含了注解的配置文件,缺一不可
如,用户类实体,生成之后是这样子的
cascade属性的可能值有
all: 所有情况下均进行关联操作,即save-update和delete。
none: 所有情况下均不进行关联操作。这是默认值。
save-update: 在执行save/update/saveOrUpdate时进行关联操作。
delete: 在执行delete 时进行关联操作。
all-delete-orphan: 当一个节点在对象图中成为孤儿节点时,删除该节点。
比如在一个一对多的关系中,Student包含多个book,当在对象关系中删除一个book时,
此book即成为孤儿节点。
hibernate_Criteria用法『转』
外键查询
- 对于外键本身
public Resume findByUserId(Long id) {
Criteria cr=getCurrentSession().createCriteria(Resume.class);
cr.add(Restrictions.eq("user.id",id));
return (Resume) cr.list().get(0);
} - 对于外键对象的属性
public Resume findByAttr(Attr attr) {
Criteria cr=getCurrentSession().createCriteria(Resume.class);
cr.createAlias("user","u");
cr.add(Restrictions.eq("u.attr",attr));
return cr.list();
}
hibernate_Restrictions用法『转』
方法 | 说明 |
Restrictions.eq | = |
Restrictions.allEq | 利用Map来进行多个等于的限制 |
Restrictions.gt | > |
Restrictions.ge | >= |
Restrictions.lt | < |
Restrictions.le | <= |
Restrictions.between | BETWEEN |
Restrictions.like | LIKE |
Restrictions.in | in |
Restrictions.and | and |
Restrictions.or | or |
Restrictions.isNull | 判断属性是否为空,为空则返回true |
Restrictions.isNotNull | 与isNull相反 |
Restrictions.sqlRestriction | 用SQL限定查询 |
Order.asc | 根据传入的字段进行升序排序 |
Order.desc | 根据传入的字段进行降序排序 |
MatchMode.EXACT | 字符串精确匹配.相当于"like 'value'" |
MatchMode.ANYWHERE | 字符串在中间匹配.相当于"like '%value%'" |
MatchMode.START | 字符串在最前面的位置.相当于"like 'value%'" |
MatchMode.END | 字符串在最后面的位置.相当于"like '%value'" |
Disjunction:逻辑或【or】
Conjunction:逻辑与【and】
一、进行子查询并分页
背景:
有一张活动表(volunteer_activity)
和一张活动报名表(volunteer_sign_up)–存放志愿者活动报名记录
要求:查出志愿者参加的活动和未参加的活动
代码:
/**
* 查询已加入的活动
* @param key
* @param setPageSize
* @return
*/
@Override
public PageBean findAllVolunteerJoinActivity(String key, PageBean<VolunteerActivityEntity> setPageSize, String userId) { Session session = sessionFactory.openSession(); /**
* hibernate 利用子查询实现 exists 功能
*/
Criteria criteria = session.createCriteria(VolunteerActivityEntity.class, "activity");
DetachedCriteria detachedCriteria = DetachedCriteria.forClass(VolunteerSignUpEntity.class,"signUp");
detachedCriteria.add(Restrictions.eq("volunteerId", userId));
detachedCriteria.add(Property.forName("activity.activityId").eqProperty("signUp.activityId"));
criteria.add(Subqueries.exists(detachedCriteria.setProjection(Projections.property("signUp.signUpId"))));//这里改为notExists就是查询未参加的活动了 if (key != null && !key.equals("")) {
//搜索
List list = criteria.add(
Restrictions.or(
Restrictions.or(Restrictions.like("activityCode", key, MatchMode.ANYWHERE)),
Restrictions.or(Restrictions.like("activityTitle", key, MatchMode.ANYWHERE)),
Restrictions.or(Restrictions.like("activityContent", key, MatchMode.ANYWHERE)),
Restrictions.or(Restrictions.like("activityLeader", key, MatchMode.ANYWHERE))))
.setFirstResult((setPageSize.getCurrPage() - 1) * setPageSize.getPageSize() )
.setMaxResults((setPageSize.getCurrPage() - 1) * setPageSize.getPageSize() + setPageSize.getPageSize()).list();
setPageSize.setRows(list);
} else {
setPageSize.setRows(criteria.setFirstResult((setPageSize.getCurrPage() - 1) * setPageSize.getPageSize())
.setMaxResults((setPageSize.getCurrPage() - 1) * setPageSize.getPageSize() + setPageSize.getPageSize()).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list());
} session.close(); return setPageSize;
}
查询结果:
Hibernate:
select
this_.activity_id as activity1_3_0_,
this_.activity_code as activity2_3_0_,
this_.activity_content as activity3_3_0_,
this_.activity_end_time as activity4_3_0_,
this_.activity_leader as activity5_3_0_,
this_.activity_people_num as activity6_3_0_,
this_.activity_sign_end_time as activity7_3_0_,
this_.activity_sign_start_time as activity8_3_0_,
this_.activity_start_time as activity9_3_0_,
this_.activity_title as activit10_3_0_
from
volunteer_activity this_
where
exists (
select
signUp_.sign_up_id as y0_
from
volunteer_sign_up signUp_
where
signUp_.volunteer_id=?
and this_.activity_id=signUp_.activity_id
) limit ?
二、利用逻辑对象进行多条件查询
背景:
有一张竞赛表(competition)
要求:给一个部门id,查出本部门的竞赛,并模糊参训
代码:
@Override
public PageBean findByDept(Integer deptId, String key, PageBean<CompetitionEntity> pageBean) { Session session = sessionFactory.openSession(); Criteria criteria = session.createCriteria(CompetitionEntity.class); //TODO 伪外键查询--首要条件
criteria.add(Restrictions.eq("deptId", deptId)); if (key != null && !key.equals("")) { //搜索--实现:where deptId=? and (xxx like ? or xxx like ?...)
Disjunction dis = Restrictions.disjunction();//多个or可以拼接
dis.add(Restrictions.like("itemName", key, MatchMode.ANYWHERE));
List list = criteria.add(dis)
.setFirstResult((pageBean.getCurrPage() - 1) * pageBean.getPageSize() )
.setMaxResults(pageBean.getPageSize()).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();
pageBean.setRows(list);
} else { pageBean.setRows(
criteria.setFirstResult((pageBean.getCurrPage() - 1) * pageBean.getPageSize())
.setMaxResults(pageBean.getPageSize()).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list());
} pageBean.setTotal(Math.toIntExact((Long) session.createCriteria(CompetitionEntity.class).add(Restrictions.eq("deptId", deptId))
.setProjection(Projections.rowCount()).uniqueResult())); session.close(); return pageBean;
}
查询结果:
Hibernate:
select
this_.item_id as item_id1_2_0_,
this_.awardee as awardee2_2_0_,
this_.dept_id as dept_id3_2_0_,
this_.dept_name as dept_nam4_2_0_,
this_.item_name as item_nam5_2_0_,
this_.match_id as match_id6_2_0_,
this_.match_name as match_na7_2_0_,
this_.prize_grade as prize_gr8_2_0_,
this_.prize_img as prize_im9_2_0_,
this_.prize_level as prize_l10_2_0_,
this_.prize_time as prize_t11_2_0_,
this_.teacher_id as teacher12_2_0_,
this_.teacher_name as teacher13_2_0_
from
competition this_
where
this_.dept_id=?
and (
this_.item_name like ?
) limit ?
三、外键查询
背景:
有一张教师表(sys_user),与部门表(dept)存在外键约束;
注:
生成实体时,可以双向多对一,一个部门对应多个老师,但电脑吃不消
也可以用单向一对一,只对教师进行关联,这个最简单,为使用这个要求:给一个部门id,查出本部门的竞赛,并模糊参训
代码:
@Override
public PageBean findByDept(Integer deptId, String key, PageBean<TeacherEntity> pageBean) { Session session = sessionFactory.openSession(); Criteria criteria = session.createCriteria(TeacherEntity.class);
Criteria criteriaForCount = session.createCriteria(TeacherEntity.class);//用于获取数据库记录数 //TODO 外键查询
criteria.createAlias("dept", "dept").
add(Restrictions.eq("dept.deptId", deptId));
criteriaForCount.createAlias("dept", "dept").
add(Restrictions.eq("dept.deptId", deptId)); if (key != null && !key.equals("")) { //搜索--实现:where deptId=? and (xxx like ? or xxx like ?...)
Disjunction dis = Restrictions.disjunction();//多个or可以拼接
dis.add(Restrictions.like("teacherCode", key, MatchMode.ANYWHERE));
dis.add(Restrictions.like("teacherName", key, MatchMode.ANYWHERE));
List list = criteria.add(dis)
.setFirstResult((pageBean.getCurrPage() - 1) * pageBean.getPageSize() )
.setMaxResults(pageBean.getPageSize()).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list();
pageBean.setRows(list);
} else {
pageBean.setRows(criteria.setFirstResult((pageBean.getCurrPage() - 1) * pageBean.getPageSize())
.setMaxResults(pageBean.getPageSize()).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY).list());
} pageBean.setTotal(Math.toIntExact((Long) criteriaForCount.setProjection(Projections.rowCount()).uniqueResult())); session.close(); return pageBean;
}
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