@PersistenceContext
private EntityManager em;

BigDecimal totals = new BigDecimal(0);
StringBuffer sql= new StringBuffer("SELECT SUM(total) FROM Order WHERE state = 1");
if (StringUtils.isNotBlank(order.getOrderNo())) {
? ? sql.append(" AND orderNo = ").append(order.getOrderNo());
}
if (StringUtils.isNotBlank(orderTime)) {
? ? sql.append(" AND orderPayTime LIKE '").append(orderTime).append("%'");
}
if (order.getCustomer() != null) {
? ? //where條件后面是對(duì)象信息，不能直接傳入對(duì)象拼成sql，會(huì)報(bào)錯(cuò).
? ? sql.append(" AND customer = :customer");
}
Query query = em.createQuery(sql.toString());
if (order.getCustomer() != null) {
? ? //通過(guò)setParameter，給參數(shù)賦值.
? ? query.setParameter("customer", order.getCustomer());
}
Object result = query.getSingleResult();
if (result != null) {
? ? totals = new BigDecimal(result.toString());
}
return totals;

select count(***) from *** where *** group by ***

private List<Tuple> getCountByStatusOrSource(Integer status, Integer source, Integer userId, String startTime, String endTime, Integer timeSlot, String type) throws Exception {
        CriteriaBuilder cb = entityManager.getCriteriaBuilder();
        Date sTime = new Date(), eTime = new Date();
        CriteriaQuery<Tuple> query = cb.createTupleQuery();
        Root<AAA> root = query.from(AAA.class);//AAA是對(duì)應(yīng)數(shù)據(jù)庫(kù)的類(lèi)名，替換成自己的
        Path<Integer> statusPath = root.get("status");
        Path<String> statusNamePath = root.get("status").get("name");
        Path<Integer> sourcePath = root.get("source");
        Path<Date> operatorPath = root.get("operator");
 
        List<Predicate> predicateList = new ArrayList<>();
        if (source != null) {
            predicateList.add(
                cb.equal(sourcePath, source)
            );
        }
        if (userId != null) {
            predicateList.add(
                cb.equal(operatorPath, userId)
            );
        }
        Map timeMap = getChangedTime(startTime, endTime, timeSlot);//獲取時(shí)間的方法，具體代碼我就不沾了，自己寫(xiě)個(gè)就行了
        sTime = (Date) timeMap.get("sTime");
        eTime = (Date) timeMap.get("eTime");
       
            Expression<Date> startDateExpression = cb.literal(sTime);
            Expression<Date> endDateExpression = cb.literal(eTime);
            predicateList.add(
                cb.between(updateTimePath, startDateExpression, endDateExpression)
            );      
 
        Predicate[] predicates = new Predicate[predicateList.size()];
        predicates = predicateList.toArray(predicates);
        query.where(predicates);//where條件加上
        if ("status".equals(type)) {
            query.select(cb.tuple(statusPath, cb.count(root)));
            query.groupBy(statusPath);
        }
        
        //query.multiselect(statusPath, cb.count(root));//
        TypedQuery<Tuple> q = entityManager.createQuery(query);
        List<Tuple> result = q.getResultList();
        return result;
    }

Tuple tuple = list.get(i);
(long)tuple.get(0)獲取的是數(shù)量
(Integer)tuple.get(1)獲取的是狀態(tài)id