如何在不同实体上重用CriteriaBuilder

Question

我有两个相似的实体（表），它们具有许多相同的字段，并且也执行相似的搜索。

如何重用以下代码，而不是复制粘贴？

查询1

  CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<RentDTO> cq = cb.createQuery(RentDTO.class);

    Root<RentDTO> root = cq.from(RentDTO.class);
    List<Predicate> predicates = new ArrayList<>();

    if (params.getEast() == null || params.getWest() == null || params.getNorth() == null || params.getSouth() == null) {
        return null;
    }

    if (params.getBuilding_type().equals("any")){
        // TODO
    }
    else if (params.getBuilding_type() != null) {
        predicates.add(cb.like(root.get("building_type"), "%" + params.getBuilding_type() + "%"));
    } else {
        params.setBuilding_type(DEFAULT_BUILDING_TYPE);
        predicates.add(cb.like(root.get("building_type"), "%" + params.getBuilding_type() + "%"));
    }

    if (params.getMinBuildingFloor() != null) {
        predicates.add(cb.greaterThanOrEqualTo(root.get("building_floors"), params.getMinBuildingFloor()));
    }
    if (params.getMaxBuildingFloor() != null) {
        predicates.add(cb.lessThanOrEqualTo(root.get("building_floors"), params.getMaxBuildingFloor()));
    }

    if (params.getProperty_type().toString().equals("any") == false) {
        predicates.add(cb.like(root.get("property_type"), "%" + params.getProperty_type() + "%"));
    }

    if (params.getFloor() != -1) {
        predicates.add(cb.equal(root.get("floor"), params.getFloor()));
    }

    if (params.getMinYear() == null) {
        params.setMaxYear("2049");
    }

    if (params.getMinAge() != null && params.getMinAge() != 0) {
        Calendar cal = Calendar.getInstance();
        Date today = cal.getTime();
        cal.add(Calendar.YEAR, params.getMinAge() * -1); // to get previous year add -1
        Date minAgeYear = cal.getTime();
        predicates.add(cb.lessThanOrEqualTo(root.get("building_completed_date"), minAgeYear));
    }

    if (params.getMaxAge() != null && params.getMaxAge() != 99) {
        Calendar cal = Calendar.getInstance();
        Date today = cal.getTime();
        cal.add(Calendar.YEAR, params.getMaxAge() * -1); // to get previous year add -1
        predicates.add(cb.greaterThanOrEqualTo(root.get("building_completed_date"), cal.getTime()));
    }

    predicates.add(cb.greaterThanOrEqualTo(root.get("lot_size"), params.getMinPing() * PING_CONVERT_RATIO));
    if (params.getMaxPing() < 200) {
        predicates.add(cb.lessThanOrEqualTo(root.get("lot_size"), params.getMaxPing() * PING_CONVERT_RATIO));
    }


    try {
        String pattern = "yyyy-MM-dd";
        DateFormat df = new SimpleDateFormat(pattern);
        Date startDate = df.parse(params.getMinYear() + "-01-01");
        Date endDate = df.parse(params.getMaxYear() + "-12-31");
        predicates.add(cb.greaterThanOrEqualTo(root.get("date"),
                startDate
        ));
        predicates.add(cb.lessThanOrEqualTo(root.get("date"),
                endDate
        ));
    } catch (ParseException e) {
        e.printStackTrace();
    }

查询2

           Root<TransactionDTO> root = cq.from(TransactionDTO.class);
    List<Predicate> predicates = new ArrayList<>();

    if (params.getEast() == null || params.getWest() == null || params.getNorth() == null || params.getSouth() == null) {
        return null;
    }

    if (params.getBuilding_type().equals("any")){
        // TODO
    }
    else if (params.getBuilding_type() != null) {
        predicates.add(cb.like(root.get("building_type"), "%" + params.getBuilding_type() + "%"));
    } else {
        params.setBuilding_type(DEFAULT_BUILDING_TYPE);
        predicates.add(cb.like(root.get("building_type"), "%" + params.getBuilding_type() + "%"));
    }

    if (params.getMinBuildingFloor() != null) {
        predicates.add(cb.greaterThanOrEqualTo(root.get("building_floors"), params.getMinBuildingFloor()));
    }
    if (params.getMaxBuildingFloor() != null) {
        predicates.add(cb.lessThanOrEqualTo(root.get("building_floors"), params.getMaxBuildingFloor()));
    }

    if (params.getFloor() != -1) {
        predicates.add(cb.equal(root.get("floor"), params.getFloor()));
    }


    if (params.getProperty_type().toString().equals("any") == false) {
        predicates.add(cb.like(root.get("property_type"), "%" + params.getProperty_type() + "%"));
    }


    if (params.getMinYear() == null) {
        params.setMaxYear("2049");
    }

    if (params.getMinAge() != null && params.getMinAge() != 0) {
        Calendar cal = Calendar.getInstance();
        Date today = cal.getTime();
        cal.add(Calendar.YEAR, params.getMinAge() * -1); // to get previous year add -1
        Date minAgeYear = cal.getTime();
        predicates.add(cb.lessThanOrEqualTo(root.get("building_completed_date"), minAgeYear));
    }

    if (params.getMaxAge() != null && params.getMaxAge() != 99) {
        Calendar cal = Calendar.getInstance();
        Date today = cal.getTime();
        cal.add(Calendar.YEAR, params.getMaxAge() * -1); // to get previous year add -1
        predicates.add(cb.greaterThanOrEqualTo(root.get("building_completed_date"), cal.getTime()));
    }

    predicates.add(cb.greaterThanOrEqualTo(root.get("lot_size"), params.getMinPing() * PING_CONVERT_RATIO));
    if (params.getMaxPing() < 200) {
        predicates.add(cb.lessThanOrEqualTo(root.get("lot_size"), params.getMaxPing() * PING_CONVERT_RATIO));
    }


    try {
        String pattern = "yyyy-MM-dd";
        DateFormat df = new SimpleDateFormat(pattern);
        Date startDate = df.parse(params.getMinYear() + "-01-01");
        Date endDate = df.parse(params.getMaxYear() + "-12-31");

// System.out.println（“ Today =” + df.format（today））;             predicates.add（cb.greaterThanOrEqualTo（root.get（“ date”），                     开始日期             ））;             predicates.add（cb.lessThanOrEqualTo（root.get（“ date”），                     结束日期             ））;         } catch（ParseException e）{             e.printStackTrace（）;         }