Hibernate Annotation - 如何连接三个具有多对多关系的表

Question

1. 我有 3 个实体 USER、APPLICATION 和 ROLE。

   1. 我希望将 ID 连接到名为 USER_APP_ROLE(user_ID, application_ID, role_ID) 的表中，它们之间存在多对多关系。
   2. 我想要这种结构的原因是 - 我需要允许用户处理具有多个角色的多个应用程序。
   3. 我做了以下代码：

   用户.java @ManyToMany (targetEntity=Role.class) @JoinTable(name="USER_APPLICATION_ROLE", joinColumns=@JoinColumn(name="USER_ID"), inverseJoinColumns=@JoinColumn(name="ROLE_ID")) 私人收藏角色；

     @ManyToMany (targetEntity=Application.class)
     @JoinTable(name="USER_APPLICATION_ROLE",
     joinColumns=@JoinColumn(name="USER_ID"),
     inverseJoinColumns=@JoinColumn(name="APPLICATION_ID"))
     private Collection<Application> applications;
   
     Role.java
     @ManyToMany(mappedBy="roles", targetEntity=User.class)
     private Collection<User> users = new ArrayList<User>();
   
     Application.java
     @ManyToMany(mappedBy="applications", targetEntity=User.class)
     private Collection<User> users = new ArrayList<User>();
   

   1. 当我尝试运行以下测试时：

   user.getRoles().add(role1); user.getRoles().add(role2);

   role1.getUsers().add(user); role1.getUsers().add(user);

   role2.getUsers().add(user); role2.getUsers().add(user);

   user.getApplications().add(app1); user.getApplications().add(app2);

   app1.getUsers().add(user); app2.getUsers().add(user);

   ......

   session.beginTransaction(); 会话.保存（用户）； session.save(role1); session.save(role2); session.save(app1); session.save(app2);

   I get the following error:
   
   
   
         Hibernate: select seq_cm_user.nextval from dual
          Hibernate: select seq_role.nextval from dual
   Hibernate: select seq_role.nextval from dual
   Hibernate: select seq_application.nextval from dual
   Hibernate: select seq_application.nextval from dual
   Hibernate: insert into CM_USER (EMAIL, FIRST_NAME, LAST_NAME, MIDDLE_NAME, USERNAME, ID) values (?, ?, ?, ?, ?, ?)
   Hibernate: insert into CM_ROLE (DESCRIPTION, ID) values (?, ?)
   Hibernate: insert into CM_ROLE (DESCRIPTION, ID) values (?, ?)
   Hibernate: insert into CM_APPLICATION (CODE, DESCRIPTION, ID) values (?, ?, ?)
   Hibernate: insert into CM_APPLICATION (CODE, DESCRIPTION, ID) values (?, ?, ?)
   Hibernate: insert into USER_APPLICATION_ROLE (USER_ID, APPLICATION_ID) values (?, ?)
   Hibernate: insert into USER_APPLICATION_ROLE (USER_ID, APPLICATION_ID) values (?, ?)
   Exception in thread "main" org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update
       at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)
       at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
       at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275)
       at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:114)
       at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:109)
       at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:244)
       at org.hibernate.persister.collection.AbstractCollectionPersister.recreate(AbstractCollectionPersister.java:1179)
       at org.hibernate.action.CollectionRecreateAction.execute(CollectionRecreateAction.java:58)
       at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)
       at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:265)
       at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:188)
       at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
       at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
       at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
       at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:383)
       at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:133)
       at com.hp.gdas.capman.HibernateTest.main(HibernateTest.java:73)
   Caused by: java.sql.BatchUpdateException: ORA-01400: cannot insert NULL into ("SYSTEM"."USER_APPLICATION_ROLE"."ROLE_ID")
   
       at oracle.jdbc.driver.DatabaseError.throwBatchUpdateException(DatabaseError.java:343)
       at oracle.jdbc.driver.OraclePreparedStatement.executeBatch(OraclePreparedStatement.java:10657)
       at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
       at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
       ... 14 more
   

   6.我可能做错了方向。如果我完全做错了，请帮助并建议我任何替代方法。感谢任何帮助。

谢谢。

Answer 1

您似乎希望 USER_APPLICATION_ROLE 表包含为应用程序中的用户分配的角色。但这不是您的映射所做的。它的作用是使用此表来包含用户的角色（忽略应用程序），以及用户的应用程序（忽略角色）。

因此，您的映射是错误的。您需要将 USER_APPLICATION_ROLE 表映射为一个实体，因为它不是两个实体之间的纯连接表。例如，您可以将其命名为 UserApplicationRole。用户将具有与 UserApplicationRole 的 OneToMany 关联。 UserApplicationRole 将与 User 以及 Role 和 Application 具有 ManyToOne 关联。我强烈建议您在此表中添加一个自动生成的 ID 列，就像为您的所有实体一样。