Question

我有以下简单的设计：

Valid XHTML http://www.kawoolutions.com/media/persons-roles-reduced.png

这基本上是JPA不支持的非脱节继承的解决方法。人可以自己存在，但可以选择单个玩家实体，单个教练实体或两个实体来完成逻辑。

以下是相当容易理解的 JPA 2.0 映射（注意@Id前向关联）：

@Entity
@Table(name = "Persons")
public class Person implements Serializable
{
    @Id
    @Column(name = "id")
    private Integer id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @OneToOne(mappedBy = "person")
    private Coach coach = null;

    @OneToOne(mappedBy = "person")
    private Player player = null;

    ...
}

@Entity
@Table(name = "Players")
public class Player implements Serializable
{
    @Column(name = "registration_nbr")
    private String registrationNbr = null;

    @Id
    @OneToOne
    @JoinColumn(name = "id")
    private Person person = null;

    ...
}

@Entity
@Table(name = "Coaches")
public class Coach implements Serializable
{
    @Column(name = "license_nbr")
    private String licenseNbr = null;

    @Id
    @OneToOne
    @JoinColumn(name = "id")
    private Person person = null;

    ...
}

Player和Coach实体类几乎相同。

这里的问题是两个双向关联（mappedBy）。这些映射与EclipseLink完美配合，但Hibernate以某种方式带有AnnotationException：

Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: persons] Unable to configure EntityManagerFactory
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:374)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:56)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:48)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:32)
    at tld.persons.Main.main(Main.java:32)
Caused by: org.hibernate.AnnotationException: Unknown mappedBy in: tld.persons.model.Person.coach, referenced property unknown: tld.persons.model.Coach.person
    at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:159)
    at org.hibernate.cfg.Configuration.originalSecondPassCompile(Configuration.java:1686)
    at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1393)
    at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1345)
    at org.hibernate.ejb.Ejb3Configuration.buildMappings(Ejb3Configuration.java:1477)
    at org.hibernate.ejb.EventListenerConfigurator.configure(EventListenerConfigurator.java:193)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:1096)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:278)
    at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:362)
    ... 4 more

当切换到老派JPA 1.0映射时，所有运行都会再次正常运行。 Hibernate似乎在上面的映射中遇到了问题。

我已经看了很多其他的问题报告，事实上hibernate.org上的论坛充满了类似的未解决的问题，但是我找不到任何关于为什么会抛出异常的线索。

对我而言，它似乎是一个Hibernate错误。任何人都可以证实吗？（注意我正在使用Hibernate 3.6）

Answer 1

如果我们忘记在 persistence.xml 中声明实体类，则会遇到此问题。

Answer 2

可怕的错误。正如我所说EclipseLink没有任何问题。在这里查看错误报告（并投票）：

http://opensource.atlassian.com/projects/hibernate/browse/HHH-5695

Answer 3

确保注记类中的引用属性名称和setter getter方法名称应该相同例如：我有两个classess Cat和Dog有一对一的关系

在Cat课程中

class Cat {                                           
private Dog doggy;

    @OneToOne(fetch = FetchType.LAZY)
    @PrimaryKeyJoinColumn
    public Dog getdoggy() {
        return this.doggy;
    }
    public void setdoggy(Dog doggy) {
        this.doggy= doggy;
    }
}

in Dog class 

class Dog {

private Cat cat;

    @OneToOne(fetch = FetchType.LAZY, mappedBy = "doggy")
    public Cat getCat() {
        return this.cat;
    }
    public void setCat(Cat cat) {
        this.cat= cat;
    }
}

Hibernate：AnnotationException：未知的mappedBy in ...在反向（mappedBy）上引用属性unknown，双向@OneToOne关联

3 个答案: