JPA通过SqlResultSetMapping和NamedNativeQuery实现DTO

@NamedNativeQuery(
        name=<font>"CarDto"</font><font>,
        query=</font><font>"select name, color from car"</font><font>,
        resultSetMapping=</font><font>"CarDto"</font><font>
)
@SqlResultSetMapping(
        name=</font><font>"CarDto"</font><font>,
        classes=@ConstructorResult(
                targetClass=CarDto.<b>class</b>,
                columns={
                    @ColumnResult(name=</font><font>"name"</font><font>),
                    @ColumnResult(name=</font><font>"color"</font><font>)
                }                
        )
)
@Entity
@Table(name = </font><font>"car"</font><font>)
<b>public</b> <b>class</b> Car implements Serializable {

    <b>private</b> <b>static</b> <b>final</b> <b>long</b> serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    <b>private</b> Long id;

    <b>private</b> String name;
    <b>private</b> String engine;
    <b>private</b> String color;
</font>

<b>public</b> <b>class</b> CarDto implements Serializable {

    <b>private</b> <b>static</b> <b>final</b> <b>long</b> serialVersionUID = 1L;

    <b>private</b> <b>final</b> String name;
    <b>private</b> <b>final</b> String color;

    <b>public</b> CarDto(String name, String color) {
        <b>this</b>.name = name;
        <b>this</b>.color = color;
    }

    <b>public</b> String getName() {
        <b>return</b> name;
    }

    <b>public</b> String getColor() {
        <b>return</b> color;
    }    

    @Override
    <b>public</b> String toString() {
        <b>return</b> <font>"CarDto{"</font><font> + </font><font>"name="</font><font> + name + </font><font>", color="</font><font> + color + '}';
    }        
}
</font>

@Repository
@Transactional
<b>public</b> <b>class</b> Dao<T, ID <b>extends</b> Serializable> implements GenericDao<T, ID> {

    @PersistenceContext
    <b>private</b> EntityManager entityManager;

    @Override
    <b>public</b> <S <b>extends</b> T> S persist(S entity) {
        
        Objects.requireNonNull(entity, <font>"Cannot persist a null entity"</font><font>);
        
        entityManager.persist(entity);

        <b>return</b> entity;
    }

    @Transactional(readOnly=<b>true</b>)
    <b>public</b> List<CarDto> fetchCars() {
        Query query = entityManager.createNamedQuery(</font><font>"CarDto"</font><font>);                
        List<CarDto> result = query.getResultList();

        <b>return</b> result;
    }

    <b>protected</b> EntityManager getEntityManager() {
        <b>return</b> entityManager;
    }
}

Service调用：
</font>

@Service
<b>public</b> <b>class</b> CarService {

    <b>private</b> <b>final</b> Dao dao;

    <b>public</b> CarService(Dao dao) {
        <b>this</b>.dao = dao;
    }

   
    <b>public</b> List<CarDto> fetchCars() {
        <b>return</b> dao.fetchCars();
    }
}