Java JPA 查询实体部分字段

前言

实现

public interface BaseService<T,ID extends Serializable>  {

List<Object[]> findAllByNavtiveSQLBase(String sql);

Page<Object[]> findAllByNavtiveSQLPagingBase(String sql, Pageable pageable);
}

public abstract class BaseServiceImpl<T, ID extends Serializable> implements BaseService<T, ID>   {

@Autowired
protected BaseRepository<T, ID> baseRepository;
@PersistenceContext(unitName="primaryPersistenceUnit")
@Qualifier(value = "primaryDataSource")
@Autowired
protected EntityManager entityManager;

@Override
public List<Object[]> findAllByNavtiveSQLBase(String sql){
try {
Query query = entityManager.createNativeQuery(sql);
@SuppressWarnings("unchecked")
List<Object[]> list = query.getResultList();
System.out.println("list.size() = " + list.size());
entityManager.close();
return list;
} catch (RuntimeException ex) {
throw ex;
}
}

@Override
public Page<Object[]> findAllByNavtiveSQLPagingBase(String sql, Pageable pageable){
try {
Query query = entityManager.createNativeQuery(sql);
long total = query.getResultList().size();

Iterator<Order> orders = pageable.getSort().iterator();
String pageOrder = orders.hasNext() ? "order by" : "";
while (orders.hasNext()) {
Order order = (Order) orders.next();
pageOrder += String.format(" %s %s%s", order.getProperty(), order.getDirection(), (orders.hasNext() ? ", " : ""));
}

int size = pageable.getPageSize();
int begin = (pageable.getPageNumber() - 1) * size;
String pageSql = String.format("%s %s limit %s, %s", sql, pageOrder, begin, size);

System.out.println("pageSql = " + pageSql);
query = entityManager.createNativeQuery(pageSql);
@SuppressWarnings("unchecked")
List<Object[]> list = query.getResultList();

entityManager.close();
return new PageImpl<Object[]>(list, pageable, total);
} catch (RuntimeException ex) {
throw ex;
}
}
}

@Service
public class ServiceAttendanceRecordImpl extends BaseServiceImpl<AttendanceRecord,Integer> implements ServiceAttendanceRecord {

}

如何使用

List<Object[]> list = serviceCompanyEntityImpl.findAllByNavtiveSQLBase("SELECT A, B, C FROM T");
for (Object[] objects : list) {
for (Object object : objects) {

}
}