spring data jpa分頁查詢示例代碼
最近項目上用就hibernate+spring data jpa,一開始感覺還不錯,但是隨著對業(yè)務(wù)的復(fù)雜,要求處理一些復(fù)雜的sql,就順便研究了下,把結(jié)果記錄下,以便日后查看。用到Specification,需要繼承JpaSpecificationExecutor接口。(下面代碼有的分頁從0開始作為第一頁,有的從1開始作為作為第一頁,我也忘記,請自己測試)
DAO層:
import java.util.List; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.data.jpa.repository.JpaSpecificationExecutor; import org.springframework.data.jpa.repository.Modifying; import org.springframework.data.jpa.repository.Query; import org.springframework.stereotype.Repository; @Repository public interface CameraInfoRepo extends JpaRepository<CameraInfoPO, String>, JpaSpecificationExecutor<CameraInfoPO> { @Query("select c from CameraInfoPO c where c.deviceInfo.id = ?1") public List<CameraInfoPO> findCamerasByDeviceId(String listDeviceInfoId); //更新之后不清空緩存,在一個事務(wù)里查詢到舊數(shù)據(jù)(hibernate) @Modifying @Query(value = "update CameraInfoPO c set c.isEnabled = 1 where c.id = ?1") public void updateEnabled(String cameraId); //更新之后清空緩存,不保留舊對象(hibernate) @Modifying(clearAutomatically = true) @Query(value = "update CameraInfoPO c set c.isEnabled = 0 where c.id = ?1") public void updateUnEnabled(String cameraId); //帶條件的分頁查詢 public Page<CameraInfoPO> findByIsEnabled(Integer isEnabled, Pageable pageable); }
DAO實現(xiàn)層
import java.util.ArrayList; import java.util.List; import javax.annotation.Resource; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.TypedQuery; import javax.persistence.criteria.CriteriaBuilder; import javax.persistence.criteria.CriteriaQuery; import javax.persistence.criteria.Predicate; import javax.persistence.criteria.Root; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageImpl; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.domain.Specification; import org.springframework.stereotype.Repository; @Repository public class CameraInfoRepoImpl { @PersistenceContext private EntityManager em; @Resource private CameraInfoRepo cameraInfoRepo; public Page<CameraInfoPO> findCameraInfoByPage(Pageable pageable, Integer isEnabled) { //CriteriaBuilder,用來構(gòu)建CritiaQuery的構(gòu)建器對象 CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder(); //CriteriaQuery,它包含著查詢語句的條件各個部分,比如:select 、from、where、group by、order by等 CriteriaQuery<CameraInfoPO> criteriaQuery = criteriaBuilder.createQuery(CameraInfoPO.class); //查詢根,用于獲取查詢實例的屬性,通過CriteriaQuery的from方法獲取 Root<CameraInfoPO> rootFrom = criteriaQuery.from(CameraInfoPO.class); //查詢條件 List<Predicate> predicates = new ArrayList<Predicate>(); if (null != isEnabled) { Predicate predicate = criteriaBuilder.equal(rootFrom.get("isEnabled").as(Integer.class), isEnabled); predicates.add(predicate); } //格式化參數(shù) criteriaQuery.where(criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]))); //默認按照id排序(從小到大) criteriaQuery.orderBy(criteriaBuilder.asc(rootFrom.get("id"))); //SQL查詢對象 TypedQuery<CameraInfoPO> createQuery = em.createQuery(criteriaQuery); //分頁參數(shù) Integer pageSize = pageable.getPageSize(); Integer pageNo = pageable.getPageNumber(); //計數(shù)查詢結(jié)果條數(shù) TypedQuery<CameraInfoPO> createCountQuery = em.createQuery(criteriaQuery); // 實際查詢返回分頁對象 int startIndex = pageSize * pageNo; createQuery.setFirstResult(startIndex); createQuery.setMaxResults(pageable.getPageSize()); Page<CameraInfoPO> pageRst = new PageImpl<CameraInfoPO>(createQuery.getResultList(), pageable, createCountQuery.getResultList().size()); return pageRst; } //制造查詢條件結(jié)果(建議存放map) private Specification<CameraInfoPO> getWhereClause(final Integer isEnabled) { return new Specification<CameraInfoPO>() { public Predicate toPredicate(Root<CameraInfoPO> r, CriteriaQuery<?> q, CriteriaBuilder cb) { Predicate predicate = cb.conjunction(); if (null != isEnabled) { predicate = cb.equal(r.get("isEnabled").as(Integer.class), isEnabled); } return predicate; } }; } //單表根據(jù)查詢條件的分頁 public Page<CameraInfoPO> findCameraInfoByPageForJpa(Pageable pageable, Integer isEnabled) { Specification<CameraInfoPO> spec = getWhereClause(isEnabled); Page<CameraInfoPO> pageRst = cameraInfoRepo.findAll(spec, pageable); return pageRst; } }
還有另外一種就更簡單了,如果只是根據(jù)表里面的一個或者幾個字段,可以直接寫jpa實現(xiàn),不用復(fù)雜
Pageable pageable = new PageRequest(1, 1); Page<CameraInfoPO> page = cameraInfoRepo.findByIsEnabled(1, pageable);
以上就是本文的全部內(nèi)容,希望對大家的學(xué)習有所幫助,也希望大家多多支持腳本之家。
相關(guān)文章
關(guān)于mybatis3中幾個@Provider的使用方式
這篇文章主要介紹了關(guān)于mybatis3中幾個@Provider的使用方式,具有很好的參考價值,希望對大家有所幫助。如有錯誤或未考慮完全的地方,望不吝賜教2022-07-07探索分析Redis?AOF日志與數(shù)據(jù)持久性
這篇文章主要為大家介紹了探索分析Redis?AOF日志與數(shù)據(jù)持久性詳解,有需要的朋友可以借鑒參考下,希望能夠有所幫助,祝大家多多進步,早日升職加薪2023-12-12Java RandomAccessFile 指定位置實現(xiàn)文件讀取與寫入
這篇文章主要介紹了Java RandomAccessFile 指定位置實現(xiàn)文件讀取與寫入的相關(guān)資料,需要的朋友可以參考下2017-01-01