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jpa分页

时间:2019-08-18 09:18:51      阅读:48      评论:0      收藏:0      [点我收藏+]

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法一(本地sql查询,注意表名啥的都用数据库中的名称,适用于特定数据库的查询)

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public interface UserRepository extends JpaRepository<User, Long> {

  @Query(value = "SELECT * FROM USERS WHERE LASTNAME = ?1",
    countQuery = "SELECT count(*) FROM USERS WHERE LASTNAME = ?1",
    nativeQuery = true)
  Page<User> findByLastname(String lastname, Pageable pageable);
}
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法二(jpa已经实现的分页接口,适用于简单的分页查询)

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public interface PagingAndSortingRepository<T, ID extends Serializable>
  extends CrudRepository<T, ID> {

  Iterable<T> findAll(Sort sort);

  Page<T> findAll(Pageable pageable);
}

Accessing the second page of User by a page size of 20 you could simply do something like this:

PagingAndSortingRepository<User, Long> repository = // … get access to a bean
Page<User> users = repository.findAll(new PageRequest(1, 20));
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User findFirstByOrderByLastnameAsc();

User findTopByOrderByAgeDesc();

Page<User> queryFirst10ByLastname(String lastname, Pageable pageable);

Slice<User> findTop3ByLastname(String lastname, Pageable pageable);

List<User> findFirst10ByLastname(String lastname, Sort sort);

List<User> findTop10ByLastname(String lastname, Pageable pageable);
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//service
 Sort sort = new Sort(Sort.Direction.DESC,"createTime"); //创建时间降序排序
 Pageable pageable = new PageRequest(pageNumber,pageSize,sort);
 this.depositRecordRepository.findAllByUserIdIn(userIds,pageable);

//repository
Page<DepositRecord> findAllByUserIdIn(List<Long> userIds,Pageable pageable);
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法三(Query注解,hql语局,适用于查询指定条件的数据)

 @Query(value = "select b.roomUid from RoomBoard b where b.userId=:userId and b.lastBoard=true order by  b.createTime desc")
    Page<String> findRoomUidsByUserIdPageable(@Param("userId") long userId, Pageable pageable);
Pageable pageable = new PageRequest(pageNumber,pageSize);
Page<String> page = this.roomBoardRepository.findRoomUidsByUserIdPageable(userId,pageable);
List<String> roomUids = page.getContent();

可以自定义整个实体(Page<User>),也可以查询某几个字段(Page<Object[]>),和原生sql几乎一样灵活。

 

法四(扩充findAll,适用于动态sql查询)

public interface UserRepository extends JpaRepository<User, Long> {

    Page<User> findAll(Specification<User> spec, Pageable pageable);
} 
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@Service
public class UserService {

    @Autowired
    private UserRepository userRepository;

    public Page<User> getUsersPage(PageParam pageParam, String nickName) {
        //规格定义
        Specification<User> specification = new Specification<User>() {

            /**
             * 构造断言
             * @param root 实体对象引用
             * @param query 规则查询对象
             * @param cb 规则构建对象
             * @return 断言
             */
            @Override
            public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                List<Predicate> predicates = new ArrayList<>(); //所有的断言
                if(StringUtils.isNotBlank(nickName)){ //添加断言
                    Predicate likeNickName = cb.like(root.get("nickName").as(String.class),nickName+"%");
                    predicates.add(likeNickName);
                }
                return cb.and(predicates.toArray(new Predicate[0]));
            }
        };
        //分页信息
        Pageable pageable = new PageRequest(pageParam.getPage()-1,pageParam.getLimit()); //页码:前端从1开始,jpa从0开始,做个转换
        //查询
        return this.userRepository.findAll(specification,pageable);
    }

}
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法五(使用entityManager,适用于动态sql查询)

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@Service
@Transactional
public class IncomeService{ /** * 实体管理对象 */ @PersistenceContext EntityManager entityManager; public Page<IncomeDaily> findIncomeDailysByPage(PageParam pageParam, String cpId, String appId, Date start, Date end, String sp) { StringBuilder countSelectSql = new StringBuilder(); countSelectSql.append("select count(*) from IncomeDaily po where 1=1 "); StringBuilder selectSql = new StringBuilder(); selectSql.append("from IncomeDaily po where 1=1 "); Map<String,Object> params = new HashMap<>(); StringBuilder whereSql = new StringBuilder(); if(StringUtils.isNotBlank(cpId)){ whereSql.append(" and cpId=:cpId "); params.put("cpId",cpId); } if(StringUtils.isNotBlank(appId)){ whereSql.append(" and appId=:appId "); params.put("appId",appId); } if(StringUtils.isNotBlank(sp)){ whereSql.append(" and sp=:sp "); params.put("sp",sp); } if (start == null) { start = DateUtil.getStartOfDate(new Date()); } whereSql.append(" and po.bizDate >= :startTime"); params.put("startTime", start); if (end != null) { whereSql.append(" and po.bizDate <= :endTime"); params.put("endTime", end); } String countSql = new StringBuilder().append(countSelectSql).append(whereSql).toString(); Query countQuery = this.entityManager.createQuery(countSql,Long.class); this.setParameters(countQuery,params); Long count = (Long) countQuery.getSingleResult(); String querySql = new StringBuilder().append(selectSql).append(whereSql).toString(); Query query = this.entityManager.createQuery(querySql,IncomeDaily.class); this.setParameters(query,params); if(pageParam != null){ //分页 query.setFirstResult(pageParam.getStart()); query.setMaxResults(pageParam.getLength()); } List<IncomeDaily> incomeDailyList = query.getResultList(); if(pageParam != null) { //分页 Pageable pageable = new PageRequest(pageParam.getPage(), pageParam.getLength()); Page<IncomeDaily> incomeDailyPage = new PageImpl<IncomeDaily>(incomeDailyList, pageable, count); return incomeDailyPage; }else{ //不分页 return new PageImpl<IncomeDaily>(incomeDailyList); } } /** * 给hql参数设置值 * @param query 查询 * @param params 参数 */ private void setParameters(Query query,Map<String,Object> params){ for(Map.Entry<String,Object> entry:params.entrySet()){ query.setParameter(entry.getKey(),entry.getValue()); } }
}
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jpa分页

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原文地址:https://www.cnblogs.com/lxy061654/p/11371366.html

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