顶部＆＃34; N＆＃34;使用休眠条件

Question

上/下/随机＆＃34; N＆＃34;使用Hibernate Criteria / Projections

在每个组中的行

如何检索每个子主题的前5个问题

    DetachedCriteria criteria = DetachedCriteria.forClass(Question.class);
    ProjectionList projList = Projections.projectionList();
    projList.add(Projections.property("questionId"));
    projList.add(Projections.groupProperty("subTopicId"));
    criteria.setProjection(projList);
    List<Object> resultList = (List<Object>) getHibernateTemplate().findByCriteria(criteria);
    Iterator<Object> itr = resultList.iterator();
    List<Integer> questionIdList = new ArrayList<Integer>();
    while(itr.hasNext()){
        Object ob[] = (Object[])itr.next();
        System.out.println(ob[0]+"  --  "+ob[1]);
    }

我正在使用下面的代码暂时获取结果，Hibernate是否有任何解决方案使用Criteria API /任何其他替代方法来获得结果

   Set<Integer> getQuestionsBySubTopicWithLimit(Set<Integer> questionIdsSet, Integer subjectId, Integer limit, Integer status) {
   DetachedCriteria criteria = DetachedCriteria.forClass(Question.class);
    if(subjectId!=null && subjectId!=0){
        criteria.add(Restrictions.eq("subjectId", subjectId));
    }
    if(status!=null){
        criteria.add(Restrictions.eq("status", status));
    }
    if(questionIdsSet!=null && !questionIdsSet.isEmpty()){
        criteria.add(Restrictions.not(Restrictions.in("questionId", questionIdsSet)));
    }
    ProjectionList projList = Projections.projectionList();
    projList.add(Projections.property("questionId"));
    projList.add(Projections.property("subTopicId"));
    criteria.add(Restrictions.sqlRestriction("1=1 order by sub_topic_id, rand()"));
    criteria.setProjection(projList);
    List<Object> resultList = (List<Object>) getHibernateTemplate().findByCriteria(criteria);
    Iterator<Object> itr = resultList.iterator();
    Set<Integer> tmpQuestionIdsSet = new HashSet<Integer>();
    Integer subTopicId = 0, tmpSubTopicId = 0;
    Integer count = 0;
    while(itr.hasNext()){
        Object ob[] = (Object[])itr.next();
        if(count==0){
            subTopicId = (Integer) ob[1];
        }
        tmpSubTopicId = (Integer) ob[1];
        if(tmpSubTopicId!=subTopicId){
            subTopicId = tmpSubTopicId;
            count = 0;
        }
        count++;
        if(count<=limit){
            tmpQuestionIdsSet.add((Integer) ob[0]);
        }
    }
    return tmpQuestionIdsSet;
    }