Java hibernate/jpa 如何创建自相关的动态通用实体

Question

我想使用 JPA/hibernate 创建动态和通用的超类，该超类将针对每个层次结构模型进行扩展，例如：角色、页面、目录、部门、权限、树。 我想使用递归和java反射创建这个对象动态树

它应该是这样的：

该实体应该引用自身实体。

我希望它是完全抽象的并且没有数据库表。只有扩展实体应该有 db。

我已经尝试过实现这一目标。但是失败了这么久。 Here is my post about it

我考虑解决方案：

• @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
• @Any 和 @AnyMetaDef 映射
• @MappedSuperclass
• @Embeddable 和 @Embedded

希望有人给点建议。

Answer 1

我想出了以下设计。也可以在GitHub查看：

@MappedSuperclass
public abstract class GenericHierarchicalDictionary {

    public abstract GenericHierarchicalDictionary getParent();

    public abstract Set<? extends GenericHierarchicalDictionary> getChildren();

}

@Entity
@Table(name = "LocalFolder")
public class LocalFolder extends GenericHierarchicalDictionary {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    private LocalFolder parent;

    @OneToMany(mappedBy = "parent")
    private Set<LocalFolder> children = new HashSet<LocalFolder>();

    @Override
    public LocalFolder getParent() {
        return parent;
    }

    @Override
    public Set<LocalFolder> getChildren() {
        return children;
    }

    public void addChild(LocalFolder localFolder) {
        localFolder.parent = this;
        children.add(localFolder);
    }
}

@Entity
@Table(name = "RemoteFolder")
public class RemoteFolder extends GenericHierarchicalDictionary {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    private RemoteFolder parent;

    @OneToMany(mappedBy = "parent")
    private Set<RemoteFolder> children = new HashSet<RemoteFolder>();

    @Override
    public RemoteFolder getParent() {
        return parent;
    }

    @Override
    public Set<RemoteFolder> getChildren() {
        return children;
    }

    public void addChild(RemoteFolder localFolder) {
        localFolder.parent = this;
        children.add(localFolder);
    }
}

这是测试：

@Test
public void testTree() {
    LOGGER.debug("testAddWebResource");
    doInTransaction(new TransactionCallable<Void>() {
        @Override
        public Void execute(Session session) {
            LocalFolder rootLocalFolder = new LocalFolder();
            session.persist(rootLocalFolder);
            LocalFolder localFolder1 = new LocalFolder();
            rootLocalFolder.addChild(localFolder1);
            session.persist(localFolder1);
            LocalFolder localFolder11 = new LocalFolder();
            localFolder1.addChild(localFolder11);
            session.persist(localFolder11);

            RemoteFolder rootRemoteFolder = new RemoteFolder();
            session.persist(rootRemoteFolder);
            RemoteFolder remoteFolder1 = new RemoteFolder();
            rootRemoteFolder.addChild(remoteFolder1);
            session.persist(remoteFolder1);
            RemoteFolder remoteFolder11 = new RemoteFolder();
            remoteFolder1.addChild(remoteFolder11);
            session.persist(remoteFolder11);
            return null;
        }
    });
}