我正在使用EclipseLink 2.4.1和JPA 2.0.在我的示例中,我有以下类定义：

@Entity

public class Shepard {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

@Column(name = "id")

private Long id;

@OneToMany(mappedBy = "shepard", cascade = CascadeType.ALL, fetch = FetchType.LAZY)

private List sheeps;

public void addSheep(Sheep sheep) {

if (sheep != null) {

if (sheeps == null) {

sheeps = new ArrayList<>();

}

if (!sheeps.contains(sheep)) {

sheeps.add(sheep);

}

}

}

}

@Entity

public class Sheep {

@Id

@GeneratedValue(strategy=GenerationType.IDENTITY)

@Column(name = "id")

private Long id;

@Column(name = "name")

private String name;

@ManyToOne(fetch = FetchType.EAGER, optional = false)

@JoinColumn(name="shepard_id")

private Shepard shepard;

public Sheep(Shepard shepard, String name) {

this.shepard = shepard;

this.name = name;

shepard.addSheep(this);

}

}

现在,当我编写Junit测试并执行以下操作时.注意,Sheep构造函数调用Shepard.addSheep(Sheep)！

EntityManagerFactory emf = Persistence.createEntityManagerFactory("data");

EnttyManager em = emf.createEntityManager();

Shepard shepard = new Shepard();

// I Persist Shepard

em.getTransaction().begin();

em.persist(shepard);

em.getTransaction().commit();

// II Persist Tilda

Sheep tilda = new Sheep(shepard, "Tilda");

em.getTransaction().begin();

em.persist(tilda);

em.getTransaction().commit();

// III Persist Martha via Shepard

Sheep martha = new Sheep(shepard, "Martha");

em.getTransaction().begin();

em.merge(shepard);

em.getTransaction().commit();

然后为Sheep的命名查询,我得到了“Tilda”的重复条目！

当我编码时,这不会发生

em.persist(martha);

相反,作为最后一个实体管理员访问.

分析调试输出,我可以看到在II之后有一个[id = 1]的Shepard对象和一个[id = 1]的Sheep对象.

在III之前和之后,Shepard拥有两个参考绵羊的参考资料,其中Tilda为[id = 1],Martha为[id = null].

在III之后,Shepard持有两个羊的参考,其中[id = 2]为Tilda,[id = 3]为Martha.

从EclipseLink调试输出中,我可以看到III在Sheep表中发出了两个insert语句.

在数据库中最终有三个Sheep条目,其中id为上面列出的.

此外,我收到以下错误：

[EL Warning]: 2013-06-21 09:53:26.631--UnitOfWork(221387686)--Thread(Thread[main,5,main])--Exception [EclipseLink-7251] (Eclipse Persistence Services - 2.4.1.v20121003-ad44345): org.eclipse.persistence.exceptions.ValidationException

Exception Description: The attribute [id] of class [Sheep] is mapped to a primary key column in the database. Updates are not allowed.

这是EclipseLink的错误吗？或者我做错了什么,这里？