我们项目用的JPA实现与数据库的交互，这次遇到了一个需求要对订单进行一定规则的排序。因为之前项目都是用的pageable对返回数据进行封装，pageable本身就有对排序的处理，但是jpa还是刚还是用，所以查了下资料，发现也可以对数据进行排序，特此记录。
把Predicate应用到CriteriaQuery中去,因为还可以给CriteriaQuery添加其他的功能，比如排序、分组啥的。如下图使我们的源代码：
首先对已删除数据和locationInfoId对数据进行过滤，然后根据deliveryType，orderPaytime字段对数据进行排序，前三种deliveryType的订单排在前面，并按orderPaytime进行升序排列，后两种类型的订单排在后面，也按orderPaytime进行升序排列。
Specification specification = (Specification<ShipOrderInfo>) (root, criteriaQuery, criteriaBuilder) -> { List<Predicate> predicates = new ArrayList<>(); // 排除逻辑删除数据 predicates.add(criteriaBuilder.equal(root.get("dataStatus"), AuditModel.DATA_STATUS_ACTVIE)); if (null != locationInfoId) { predicates.add(criteriaBuilder.equal(root.get("locationInfoId"), locationInfoId)); } if (!StringUtils.isEmpty(shipStatus)) { CriteriaBuilder.In<Object> in = criteriaBuilder.in(root.get("orderLatestStatus")); String[] shipStatusArray = StringUtils.split(shipStatus, ','); Arrays.stream(shipStatusArray).forEach(x -> { in.value(Integer.valueOf(x)); }); predicates.add(in); } criteriaQuery.where(predicates.toArray(new Predicate[predicates.size()])); criteriaQuery.orderBy( //先根据 deliveryType 权重升序排 criteriaBuilder.asc( criteriaBuilder.selectCase() .when(criteriaBuilder.equal( root.get("deliveryType"), "Home delivery 2h"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "C&C 2h"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "tmalldss"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "Home delivery"), 3) .when(criteriaBuilder.equal( root.get("deliveryType"), "C&C"), 3) .otherwise(99)), //再根据 orderPaytime 升序排 criteriaBuilder.asc(root.get("orderPaytime")) ); return criteriaQuery.getRestriction(); }; 当然了，还有其他的排序用法：like做模糊匹配，gt筛选大于填入参数的数据，lt筛选小于输入参数的数据。 Specification<ShipOrderInfo> spec = new Specification<ShipOrderInfo>() { public Predicate toPredicate(Root<ShipOrderInfo> root, CriteriaQuery<?> query, CriteriaBuilder cb) { Predicate p1 = cb.like(root.get("name").as(String.class), "%"+um.getName()+"%"); Predicate p2 = cb.equal(root.get("uuid").as(Integer.class), um.getUuid()); Predicate p3 = cb.gt(root.get("age").as(Integer.class), um.getAge()); //把Predicate应用到CriteriaQuery中去,因为还可以给CriteriaQuery添加其他的功能，比如排序、分组啥的 query.where(cb.and(p3,cb.or(p1,p2))); //添加排序的功能 query.orderBy(cb.desc(root.get("uuid").as(Integer.class))); return query.getRestriction(); } }; 还有复杂条件组合查询 Specification specification = (Specification<ShipOrderInfo>) (root, criteriaQuery, criteriaBuilder) -> { List<Predicate> predicates = new ArrayList<>(); // 排除逻辑删除数据 predicates.add(criteriaBuilder.equal(root.get("dataStatus"), AuditModel.DATA_STATUS_ACTVIE)); if (null != locationInfoId) { predicates.add(criteriaBuilder.equal(root.get("locationInfoId"), locationInfoId)); } if (!StringUtils.isEmpty(shipStatus)) { CriteriaBuilder.In<Object> in = criteriaBuilder.in(root.get("orderLatestStatus")); String[] shipStatusArray = StringUtils.split(shipStatus, ','); Arrays.stream(shipStatusArray).forEach(x -> { in.value(Integer.valueOf(x)); }); predicates.add(in); } criteriaQuery.where(predicates.toArray(new Predicate[predicates.size()])); criteriaQuery.orderBy( //先根据 deliveryType 权重升序排 criteriaBuilder.asc( criteriaBuilder.selectCase() .when(criteriaBuilder.equal( root.get("deliveryType"), "Home delivery 2h"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "C&C 2h"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "tmalldss"), 1) .when(criteriaBuilder.equal( root.get("deliveryType"), "Home delivery"), 3) .when(criteriaBuilder.equal( root.get("deliveryType"), "C&C"), 3) .otherwise(99)), //再根据 orderPaytime 升序排 criteriaBuilder.asc(root.get("orderPaytime")) ); return criteriaQuery.getRestriction(); };
