HQL and criteria select-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_15826/article/details/81934357

本文介绍了一种使用Hibernate框架查询FriendBean实例的方法。通过Criteria API并结合Restrictions进行条件筛选，实现了根据用户ID、好友ID及分组ID查找特定FriendBean记录的功能。

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    @Override
    public FriendBean findFriendBean(final FriendBean friendBean) {
//        return (FriendBean) this.getHibernateTemplate().execute(
//                new HibernateCallback() {
//                    public Object doInHibernate(Session session)
//                            throws HibernateException, SQLException {
//                        Query query = session
//                                .createQuery("FROM FriendBean f WHERE f.id.userid=? AND f.id.friendid=? AND f.id.groupid=?")
//                                .setParameter(0, friendBean.getId().getUserid())
//                                .setParameter(1, friendBean.getId().getFriendid())
//                                .setParameter(2, friendBean.getId().getGroupid());
//                        return query.uniqueResult();
//                    }
//                });

        return (FriendBean) this.getHibernateTemplate().execute(new HibernateCallback() {
            public Object doInHibernate(Session session) throws HibernateException, SQLException {
                Criteria criteria = session.createCriteria(FriendBean.class);
                // criteria.setProjection(Projections.count("userId"));
                if(null!= friendBean){
                    if(null!=friendBean.getId().getUserid()){
                        criteria.add(Restrictions.eq("id.userid", friendBean.getId().getUserid()));
                    }
                    if(null!=friendBean.getId().getFriendid()){
                        criteria.add(Restrictions.eq("id.friendid", friendBean.getId().getFriendid()));
                    }
                    if(null!=friendBean.getId().getGroupid()){
                        criteria.add(Restrictions.eq("id.groupid", friendBean.getId().getGroupid()));
                    }
                }
                Object result = criteria.uniqueResult();
                //criteria.setProjection(null);
                return result;
            }
        });

    }