Hibernate 如何获取新持久化实体的复合ID对象？

我正在尝试获取新持久化到DB的对象的（可嵌入的）复合id。我在Hibernate4.3.5中使用mysql（myisam）

插入操作本身成功，但创建的java对象的类别id始终为空，即使我刷新了对象并提交了事务。 但这只发生在复合id对象上。在单id对象中，我总是将新id取回

我忘了什么吗？感谢您的帮助

先谢谢你

本

朱尼特：

@Test
public void _1testInsertCombinedEntity() {
    CategoryDao catDao = new CategoryDao();

    Category cat = new Category();
    CategoryId catId = new CategoryId();
    catId.setCategoryCustomerId(1l);
    cat.setCategoryId(catId);

    cat.setCategoryName(catName);
    cat.setCategoryDescr("Hello World. This is a test");
    cat.setCategoryPrintable(true);
    cat.setCategoryBookable(true);

    cat = catDao.save(cat);

    Assert.assertNotNull(cat.getCategoryId().getCategoryId());

}

类别：

    @Entity
@Table(name = "category")
public class Category implements ICombinedIdEntity {

    @EmbeddedId
    private CategoryId categoryId;

 ........

类别

@Embeddable
public class CategoryId implements Serializable, ICombinedId<Long, Long> {

    /**
     * 
     */
    private static final long serialVersionUID = -7448052477830797280L;

    @Column(name = "category_id", nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long              categoryId;

    @Column(name = "category_customer_id", nullable = false)
    private Long              categoryCustomerId;

    public Long getCategoryId() {
        return this.categoryId;
    }

    public void setCategoryId(Long categoryId) {
        this.categoryId = categoryId;
    }

    public Long getCategoryCustomerId() {
        return this.categoryCustomerId;
    }

    public void setCategoryCustomerId(Long categoryCustomerId) {
        this.categoryCustomerId = categoryCustomerId;
    }

---

简而言之，这是不受支持的

这是因为

@EmbeddedId

标识符意味着要分配，因此解释了为什么忽略带注释的

@GeneratedValue

字段

您可能可以使用一些JPA回调来设置insert上的值，但在开箱即用的情况下，Hibernate不会尝试设置这些值

protected T saveEntity(T entity) {
        startTransaction();
        System.out.println("Trying to save " + entity);
        this.persistenceEngine.getEntityManager().persist(entity);
        this.persistenceEngine.getEntityManager().flush();
        commitCurrentTransaction();
        clear();
        return entity;
    }