Spring Data Jpa 自定義 repository 轉 DTO

近期項目中需要 關聯 幾張表再把字段轉出來，在這里記錄以下，我感覺網上寫的都不太規范和清晰。

@Entity
@SqlResultSetMapping(
        name="TestMapping",
        entities = {
                @EntityResult(
                        entityClass = com.xxx.xx.data.model.TestEntity.class,
                        fields = {
                                @FieldResult(name="id",column="id"),
                                @FieldResult(name="localTime",column="time"),
                                @FieldResult(name="maximumAppointment",column="maxAppointment"),
                        }
                )
        }
)
@NamedNativeQuery(name="getTestQuery",
        query="select tableC.id as id,tableB.time,tableC.maximumAppointment as maxAppointment from tableB " +
                "                              inner join tableA on tableA.id = tableB.tableAId " +
                "                              inner join tableC on tableB.id = tableC.tableBId " +
                "                              inner join custom on custom.id = tableA.customId " +
                "where " +
                "   tableA.locationId = :locationId" +
                "   and custom.id = :customId" +
                "   and tableB.deleted = false ", resultSetMapping="TestMapping")
@Data
public class TestEntity {
    @Id
    private String id;
    private LocalTime localTime;
    private Integer maximumAppointment;
}

需要聲明接口：

@Repository
public interface TestEntityRepository extends JpaRepository<TestEntity,String> {

    @Query(name="getTestQuery")
    List<TestEntity> getTestQuery(String locationId, String customId);

}

若不想聲明接口，那可以用EntityManager 來實現。 

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();