@ManyToOne(fetch=fetchType.lazy）对非主键引用的列不起作用

Question

这是我的模型：

DummyB -> DummyA

以下是表格：

create table dummyA  (
  id number(18,0), --pk
  name varchar2(20) -- unique field
);

create table dummyB  (
  id number(18,0),
  dummya_id number(18,0),
  dummya_name varchar2(20)
);

这些实体是：

@Entity
public class DummyA implements Serializable {

    private Long id;
    private String name;

    @Id
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

@Entity
public class DummyB implements Serializable {

    private Long id;
    private DummyA dummyA;

    @Id
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    /* Case 1: mapping DummyB -> DummyA by DummyA NON primary key (field name) */
    // @ManyToOne(fetch = FetchType.LAZY)
    // @JoinColumn(name = "dummya_id")
    // public DummyA getDummyA() {
    // return dummyA;
    // }

    /* Case 2: mapping DummyB -> DummyA by DummyA primary key */
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "dummya_name", referencedColumnName = "name")
    @LazyToOne(LazyToOneOption.PROXY)
    public DummyA getDummyA() {
        return dummyA;
    }

    public void setDummyA(DummyA dummyA) {
        this.dummyA = dummyA;
    }

}

public class DummyTest {

    @Autowired
    HibernateTransactionManager transactionManager;

    @Test
    @Transactional
    public void testFindDummyB() throws DAOException {
        Long idDummyB = 2L;

        Session sesshtml" target="_blank">ion = getCurrentHibernateSession();

        List lst = session.createCriteria(DummyB.class)
                .add(Restrictions.eq("id", idDummyB)).list();

        assertTrue(lst.size() > 0);
    }

    private Session getCurrentHibernateSession() {
        return this.transactionManager.getSessionFactory().getCurrentSession();
    }

}

我得库：

• org.hibernate:hibernate-core:jar:4.2.17.final:compile
• org.hibernate.common：hibernate-commons-annotations:jar:4.0.2.final:compile
• org.hibernate.javax.persistence:hibernate-jpa-2.0-api:jar:1.0.1.final:compile
• org.hibernate：hibernate-validator:jar:4.3.2.final:provided

其他我已经尝试过的事情：

谢谢你。

Answer 1

万一有人对此仍有问题，我们将其按以下方式工作：

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "dummya_name", referencedColumnName = "name", insertable = false, updatable = false),
@LazyToOne(LazyToOneOption.NO_PROXY)
public DummyA getDummyA() {
    if (fieldHandler != null) {
        return (DummyA) fieldHandler.readObject(this, "dummyA", dummyA);
    }
    return dummyA;
}

public void setDummyA(DummyA dummyA) {
    if (fieldHandler != null) {
        this.dummyA = (DummyA ) fieldHandler.writeObject(this, "dummyA", this.dummyA, dummyA);
        return;
    }
    this.dummyA= dummyA;
}

@Override
public void setFieldHandler(FieldHandler fieldHandler) {
    this.fieldHandler = fieldHandler;
}

@Override
public FieldHandler getFieldHandler() {
    return fieldHandler;
}

在Hibernate惰性加载中解释得很好，用于反向一对一的解决方案--这是如何工作的？

正如@Alina-Petukhova提到的，DummyB类必须实现FieldHandled接口。