JPA自定义查询List转Page分页失效，修改page/size参数无响应如何解决？

你当前的实现属于典型的假分页，核心问题出在Repository层的自定义查询逻辑：

• 调用entityManager.createQuery(query.where(predicate)).getResultList()时，没有给查询应用分页参数，会把所有符合筛选条件的Car记录全部从数据库查出来，无论传入的page和size是什么值
• 后续用全量列表封装PageImpl时，总条数直接传了当前全量列表的长度，就算Page对象里携带分页参数，返回的内容还是全量数据，因此分页参数修改不会生效

第一步：修改Repository层自定义搜索逻辑 #

需要调整三处逻辑：先构建统一查询条件、再查询符合条件的总记录数、最后给查询应用分页+排序参数后查询当前页数据，修改后代码如下：

@Override
public Page<Car> search(Pageable pageable, String brand, String model, String type, Integer registrationYear, String color,
                        String fuel, String transmission, String doors, double price) {
    int var = 0;
    CriteriaBuilder cb = entityManager.getCriteriaBuilder();
    // 1. 构建公共查询条件
    CriteriaQuery<Car> query = cb.createQuery(Car.class);
    Root<Car> car = query.from(Car.class);
    query.select(car);
    Predicate predicate = cb.greaterThan(car.get("id"), var);

    if (brand != null) predicate = cb.and(predicate, cb.equal(car.get("brand"), brand));
    if (model != null) predicate = cb.and(predicate, cb.equal(car.get("model"), model));
    if (type != null) predicate = cb.and(predicate, cb.equal(car.get("type"), type));
    if (registrationYear != null)
        predicate = cb.and(predicate, cb.equal(car.get("registrationNumber"), registrationYear));
    if (color != null) predicate = cb.and(predicate, cb.equal(car.get("color"), color));
    if (fuel != null) predicate = cb.and(predicate, cb.equal(car.get("fuel"), Fuel.stringToFuelEnum(fuel)));
    if (transmission != null)
        predicate = cb.and(predicate, cb.equal(car.get("transmission"), Transmission.stringToTransmissionEnum(transmission)));
    if (doors != null) predicate = cb.and(predicate, cb.equal(car.get("doors"), doors));
    if (price != 0) predicate = cb.and(predicate, cb.lessThan(car.get("price"), price));
    query.where(predicate);

    // 2. 新增：查询符合条件的总记录数，用于Page对象计算总页数
    CriteriaQuery<Long> countQuery = cb.createQuery(Long.class);
    Root<Car> countRoot = countQuery.from(Car.class);
    countQuery.select(cb.count(countRoot)).where(cb.and(predicate, cb.greaterThan(countRoot.get("id"), var)));
    Long total = entityManager.createQuery(countQuery).getSingleResult();

    // 3. 新增：给查询应用分页+排序参数，查询当前页对应的数据
    List<Car> carList = entityManager.createQuery(query)
            .setFirstResult((int) pageable.getOffset()) // 分页起始位置
            .setMaxResults(pageable.getPageSize()) // 每页最多返回条数
            .getResultList();

    // 4. 传入真实总条数封装正确的Page对象
    return new PageImpl<>(carList, pageable, total);
}

第二步（可选优化）：简化Controller层参数 #

Spring Boot默认配置下Pageable会自动解析请求中的page、size、sort参数，不需要手动重复声明page和size参数，简化后代码如下：

@GetMapping("/find")
ResponseEntity<Page<CarDTO>> readAllCarsFiltered(@PageableDefault(page = 0, size = 5) Pageable pageable,
                                                 @RequestParam(required = false) String brand,
                                                 @RequestParam(required = false) String model,
                                                 @RequestParam(required = false) String type,
                                                 @RequestParam(required = false) Integer registrationYear,
                                                 @RequestParam(required = false) String color,
                                                 @RequestParam(required = false) String fuel,
                                                 @RequestParam(required = false) String transmission,
                                                 @RequestParam(required = false) String doors,
                                                 @RequestParam(required = false, defaultValue = "9999999999") double price) {
    return ResponseEntity.ok(carService.customerSearch(pageable,
            brand, model, type, registrationYear, color, fuel, transmission, doors, price));
}

通过@PageableDefault注解可以直接配置默认分页参数，无需单独声明page和size的默认值。

内容的提问来源于stack exchange，提问作者Patryk Chojnacki