有时候我们需要用jpa实现如下sql查询：
select * from tableA A where A.EVALUATION_ITEM3 + A.EVALUATION_ITEM2 + A.EVALUATION_ITEM1 < 12;

这个条件怎么通过jpa的 javax.persistence.criteria.Predicate类实现呢？

方法：

Specification<ServiceMainVo> specification = new Specification<ServiceMainVo>() {
        
        @Override
        public Predicate toPredicate(Root<ServiceMainVo> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            List<Predicate> list = new ArrayList<>();
            
            //小区sid条件
            String apartmentSid = StringUtil.getStr(param.get("apartmentSid"));
            if(!"".equals(apartmentSid)){
                Predicate apartmentSidPre = cb.equal(root.get("apartmentSid"), apartmentSid);
                list.add(apartmentSidPre);
            }
            
            //服务类别条件
            String serviceCategory = StringUtil.getStr(param.get("serviceCategory"));
            if(!"".equals(serviceCategory)){
                List<String> serviceCategoryList = StringUtil.getStrList(serviceCategory, ",");
                In<String> in = cb.in(root.get("serviceCategory"));
                for (String sc : serviceCategoryList) {
                    in.value(sc);
                }
                list.add(in);
            }
            
            //状态为1
            Predicate status1Pre = cb.equal(root.get("serviceStatus"), "1");
            
            //状态在 2,20,21,22 中
            List<String> statusList = StringUtil.getStrList("2,20,21,22", ",");
            In<String> statusIn = cb.in(root.get("serviceStatus"));
            for (String status : statusList) {
                statusIn.value(status);
            }
            
            //状态为6
            Predicate status6Pre = cb.equal(root.get("serviceStatus"), "6");
            //评价总分:A.EVALUATION_ITEM3 + A.EVALUATION_ITEM2 + A.EVALUATION_ITEM1
            Expression<Integer> evaluationItemSum = cb.sum(cb.sum(root.get("evaluationItem1"), root.get("evaluationItem2")), root.get("evaluationItem3"));
            //评价总分小于12
            Predicate evaluationItemPre = cb.lessThan(evaluationItemSum, 12);
            //状态为6且评价总分小于12
            Predicate or3Pre = cb.and(status6Pre, evaluationItemPre);
            
            Predicate statusPre = cb.or(status1Pre, statusIn, or3Pre);
            list.add(statusPre);
            return cb.and(list.toArray(new Predicate[list.size()]));
        }
    };

整个条件设置实现的查询条件如下：

WHERE
            servicemai0_.APARTMENT_SID =?
        AND (
            servicemai0_.SERVICE_CATEGORY IN (?)
        )
        AND (
            servicemai0_.SERVICE_STATUS =?
            OR servicemai0_.SERVICE_STATUS IN (?, ?, ?, ?)
            OR servicemai0_.SERVICE_STATUS =?
            AND servicemai0_.EVALUATION_ITEM1 + servicemai0_.EVALUATION_ITEM2 + servicemai0_.EVALUATION_ITEM3 < 12
        )