Hibernate：如何在注释中将三个表联接到一个联接表中？

Question

请问如何使用一个共同的连接表来连接三个表？我有 USER、APPLICATION 和 ROLE 三张表，想要将它们的 ID 连接在一起，建立一个名为 USER_APP_ROLE (user.ID, application.ID, role.ID) 的表。

当我在多对多连接中删除 Application 或 Role 表时，我的代码可以工作。

我已经尝试了以下代码：

User.java

@ManyToMany (targetEntity=Role.class)
@JoinTable(name="USER_APPLICATION_ROLE",
    joinColumns=@JoinColumn(name="USER_ID"),
    inverseJoinColumns=@JoinColumn(name="ROLE_ID"))

private Collection<Role> roles;

@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>();

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();
      session.save(user);
      session.save(role1);
      session.save(role2);
      session.save(app1);
      session.save(app2);

我收到了以下错误：

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

非常感谢！

- Jemru

---

你已经解决了这个问题吗？ - Bipin Vayalu

Answer 1

问题在于您定义了与角色相关的关系和与应用程序分别相关的关系。没有声明任何特定用户是一个角色和一个应用程序的联接。

当您尝试与角色相关联时，应用程序为空，反之亦然。

以下是使用JPA映射类A、B和C之间的三方连接的示例。请注意，连接表不需要实体。

@Entity
public class A {

    @JoinTable(name = "a_b_c",
        joinColumns = @JoinColumn(name = "a_id"),
        inverseJoinColumns = @JoinColumn(name = "c_id"))
    @MapKeyJoinColumn(name = "b_id")
    @ElementCollection
    private Map<B, C> cByB = new HashMap<>();

}

@Entity
public class B {
    ...
}

@Entity
public class C {
    ...
}

- Synesso

---

@Synesso，B和C类需要ManyToMany关系。我遇到了这样的错误：Exception in thread "main" java.lang.IllegalStateException: Collection element (many-to-many) table alias cannot be empty. - Bipin Vayalu

这不允许我拥有所有可能性，比如(1,1,1),(1,2,1)。如何实现？ - Rajeshkumar

@Synesso - 你能否在这里给我指导一下：https://stackoverflow.com/questions/57311851/spring-data-jpa-create-composite-key-for-the-three-tables？ - PAA