使用Hibernate映射双向列表

我不理解Hibernate在映射双向列表时的行为。Hibernate生成的SQL语句对我来说似乎不是最优的。有人能启发我吗

场景如下：我有一对多的父子关系。我用双向列表映射这种关系

根据（章节：与索引集合的双向关联），映射应如下所示：

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

    EntityManagerFactory emf = Persistence.createEntityManagerFactory("test");
    EntityManager em = emf.createEntityManager();
    EntityTransaction tx = em.getTransaction();
    tx.begin();

    Parent newParent = new Parent();
    newParent.setName("Parent1");

    Child newChild = new Child();
    newChild.setName("Child1");

    newParent.getChildren().add(newChild);
    newChild.setParent(newParent);

    em.persist(newParent);

    em.flush();
    tx.commit();

第三条语句似乎是多余的，因为第二条语句中似乎已经设置了

parent\u id

和

parent\u index

当我更改映射并重复属性'Updateable=false，insertable=false'到父级中@JoinColumn的声明时，如下所示：

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

    EntityManagerFactory emf = Persistence.createEntityManagerFactory("test");
    EntityManager em = emf.createEntityManager();
    EntityTransaction tx = em.getTransaction();
    tx.begin();

    Parent newParent = new Parent();
    newParent.setName("Parent1");

    Child newChild = new Child();
    newChild.setName("Child1");

    newParent.getChildren().add(newChild);
    newChild.setParent(newParent);

    em.persist(newParent);

    em.flush();
    tx.commit();

客户端代码如下所示：

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

@Entity
public class Parent {

    @Id  @GeneratedValue private long id;
    @Version  private int version;
    private String name;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    @org.hibernate.annotations.IndexColumn(name = "parent_index")
    List<Child> children = new ArrayList<Child>();

...

@Entity
public class Child {

    @Id @GeneratedValue private Long id;
    @Version private int version;
    private String name;

    @ManyToOne
    @JoinColumn(name = "parent_id", updatable = false, insertable = false, nullable=false)
    private Parent parent;

...

    EntityManagerFactory emf = Persistence.createEntityManagerFactory("test");
    EntityManager em = emf.createEntityManager();
    EntityTransaction tx = em.getTransaction();
    tx.begin();

    Parent newParent = new Parent();
    newParent.setName("Parent1");

    Child newChild = new Child();
    newChild.setName("Child1");

    newParent.getChildren().add(newChild);
    newChild.setParent(newParent);

    em.persist(newParent);

    em.flush();
    tx.commit();

我正在使用hibernate entitymanager 3.4.0.GA

---

我错过了什么？是Hibernate参考指南不正确，还是我忽略了什么？

好的，我没有充分阅读注释参考指南

第二章明确规定：

要将双向一对多映射为一对多，并将一对多端作为拥有端，您必须删除mappedBy元素，并将many-To-one@JoinColumn设置为可插入且可更新为false此解决方案显然未经优化，将产生一些额外的更新语句

在本文中重复此信息可能不会有什么坏处

现在问题仍然存在：如果我在父级上重复@JoinColumn属性'Updateable=false'和'insertable=false'（请参阅第一篇文章中的代码），那么似乎不会生成额外的更新语句。。。这是合法的解决办法吗？还是这会导致另一个问题