spring data jpa分页查询示例代码

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);      //更新之后不清空缓存，在一个事务里查询到旧数据(hibernate)   @Modifying   @Query(value = "update CameraInfoPO c set c.isEnabled = 1 where c.id = ?1")   public void updateEnabled(String cameraId);      //更新之后清空缓存，不保留旧对象(hibernate)   @Modifying(clearAutomatically = true)   @Query(value = "update CameraInfoPO c set c.isEnabled = 0 where c.id = ?1")   public void updateUnEnabled(String cameraId);      //带条件的分页查询      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,用来构建CritiaQuery的构建器对象     CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();          //CriteriaQuery,它包含着查询语句的条件各个部分，比如：select 、from、where、group by、order by等     CriteriaQuery<CameraInfoPO> criteriaQuery = criteriaBuilder.createQuery(CameraInfoPO.class);          //查询根，用于获取查询实例的属性，通过CriteriaQuery的from方法获取     Root<CameraInfoPO> rootFrom = criteriaQuery.from(CameraInfoPO.class);          //查询条件     List<Predicate> predicates = new ArrayList<Predicate>();          if (null != isEnabled) {       Predicate predicate = criteriaBuilder.equal(rootFrom.get("isEnabled").as(Integer.class), isEnabled);       predicates.add(predicate);            }          //格式化参数     criteriaQuery.where(criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()])));          //默认按照id排序（从小到大）     criteriaQuery.orderBy(criteriaBuilder.asc(rootFrom.get("id")));          //SQL查询对象     TypedQuery<CameraInfoPO> createQuery = em.createQuery(criteriaQuery);          //分页参数     Integer pageSize = pageable.getPageSize();     Integer pageNo = pageable.getPageNumber();          //计数查询结果条数     TypedQuery<CameraInfoPO> createCountQuery = em.createQuery(criteriaQuery);          // 实际查询返回分页对象     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;        }      //制造查询条件结果(建议存放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;       }     };   }      //单表根据查询条件的分页   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);