https://www.cnblogs.com/hdwang/p/7843405.html
spring data jpa 分页查询
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）
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);
}
法二（jpa已经实现的分页接口，适用于简单的分页查询）
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));
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);
//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);
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);
}
@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);
} }
法五（使用entityManager，适用于动态sql查询）
@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());
}
}
}