JPA简单的分页条件查询

1，service层代码：

    @Override
    public QrCodeRecordPaging getPage(String projectId, Integer pageNumber, Integer pageSize) {
        //创建时间排序
        Sort sort = new Sort(Sort.Direction.DESC, "createAt");
        //不合法给予默认值
        if (pageNumber == null || pageSize == null || pageNumber <= 0 || pageSize <= 0) {
            pageNumber = 1;
            pageSize = Integer.MAX_VALUE;
        }
        PageRequest pageRequest = new PageRequest(pageNumber - 1, pageSize, sort);
        //返回分页信息
        Page<QrCodeRecord> all = qrCodeRecordRepository.findAll((root, query, cb) -> {
            //断言，添加断言
            Predicate p = cb.equal(root.get("projectId").as(String.class), projectId);
            return cb.and(p);
        }, pageRequest);
        return recordAssembler.toPage(all);
    }

看一下业务层就好，下面是我们自己公司封装的model,外人不要看了，没意义

2，转换封装成需要的modelPaging

public QrCodeRecordPaging toPage(Page<QrCodeRecord> all) {
        QrCodeRecordPaging paging = new QrCodeRecordPaging();
        List<QrCodeRecordModel> models = new ArrayList<>();
        all.forEach(qrCodeRecord -> models.add(toQrCodeRecordModel(qrCodeRecord)));
        paging.setData(new Items<QrCodeRecordModel>().init(models));
        paging.setFirst(all.isFirst());
        paging.setHasNext(all.hasNext());
        paging.setHasPrevious(all.hasPrevious());
        paging.setLast(all.isLast());
        paging.setPageNumber(all.getNumber() + 1);
        paging.setPageSize(all.getSize());
        paging.setTotalPage(all.getTotalPages());
        paging.setTotalElements(all.getTotalElements());
        return paging;
    }

3,返回的model

public class QrCodeRecordPaging extends PageModel<QrCodeRecordModel> {
}