spring data jpa分頁查詢示例代碼
最近項(xiàng)目上用就hibernate+spring data jpa,一開始感覺還不錯(cuò),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(gè)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(shí)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(gè)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(shí)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(rèn)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(jì)數(shù)查詢結(jié)果條數(shù)
TypedQuery<CameraInfoPO> createCountQuery = em.createQuery(criteriaQuery);
// 實(shí)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(gè)或者幾個(gè)字段,可以直接寫jpa實(shí)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(xí)有所幫助,也希望大家多多支持腳本之家。
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