Java hibernate/jpa如何創建自我相關的動態通用實體

Question

我想創建動態和通用的超類與JPA/hibernate將擴展每個層次結構模型，如：角色，頁面，目錄，部門，權限，樹。 我想用遞歸和Java反射

應該這樣看這個對象動態樹創建：

該實體應參照自身的實體。

我希望它是完全抽象的，沒有數據庫表。只有擴展的實體應該有db。

我試圖實現這一點。但是失敗那麼久。 Here is my post about it

我考慮的解決方案：

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

我希望有人會提出一些建議。

Answer 1

我想出了以下設計。您還可以檢查它GitHub：

@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); 
    } 
} 

這是測試：

@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; 
     } 
    }); 
}