Hibernate-Criteria学习笔记

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

1. 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);
   }

2. 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;
    }