在spring中使用 data jpa實現(xiàn)分頁查詢功能

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 = &#63;1") 
  public List<CameraInfoPO> findCamerasByDeviceId(String listDeviceInfoId); 
   
  //更新之后不清空緩存，在一個事務里查詢到舊數(shù)據(jù)(hibernate) 
  @Modifying 
  @Query(value = "update CameraInfoPO c set c.isEnabled = 1 where c.id = &#63;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 = &#63;1") 
  public void updateUnEnabled(String cameraId); 
   
  //帶條件的分頁查詢    
  public Page<CameraInfoPO> findByIsEnabled(Integer isEnabled, Pageable pageable); 
   
} 

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,用來構建CritiaQuery的構建器對象 
    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; 
     
  } 
   
  //制造查詢條件結果(建議存放map) 
  private Specification<CameraInfoPO> getWhereClause(final Integer isEnabled) { 
    return new Specification<CameraInfoPO>() { 
      public Predicate toPredicate(Root<CameraInfoPO> r, CriteriaQuery<&#63;> 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; 
     
  } 
   
} 

Pageable pageable = new PageRequest(1, 1); 
Page<CameraInfoPO> page = cameraInfoRepo.findByIsEnabled(1, pageable);