java - 删除多对多关系？

Question

我正在寻找如何删除@ManyToMany 的关系。我找到了这个链接:How to remove entity with ManyToMany relationship in JPA (and corresponding join table rows)?

我正在尝试这样做，但对我来说仍然不起作用。

这是我的代码

@Entity
@Table(name="aluno")
public class Aluno {
    @Id @GeneratedValue
    private Integer id;

    //informacoes gerais
    @NotNull
    private String nome;

    //federacao
    @ManyToMany(cascade = { CascadeType.REMOVE, CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH })
    @JoinTable(name = "FederacaoAluno", joinColumns = @JoinColumn(name = "id_aluno"), inverseJoinColumns = @JoinColumn(name = "id_federacao"))
    private List<Federacao> federacao;

    //get and set


@Entity
@Table(name="federacao")
public class Federacao {

    @Id @GeneratedValue
    private Integer id;

    @NotNull @Column(unique = true)
    private String federacao;

    @ManyToMany(mappedBy = "federacao")
    private List<Aluno> aluno;

    //get and set

这是我正在尝试的方法

//now works :)
public void removeFederacaoFromAluno(Federacao f){
        Federacao federacao = em.find(Federacao.class, f.getId());
        em.getTransaction().begin();        
        for(Aluno a : federacao.getAluno()){
            a.getFederacao().remove(federacao);
        }
        em.getTransaction().commit();
    }

有什么想法吗？

/** 异常 */

Exception in thread "AWT-EventQueue-0" 23:29:49,441 DEBUG [org.hibernate.ejb.AbstractEntityManagerImpl] - Mark transaction for rollback
java.lang.IllegalArgumentException: Removing a detached instance br.com.iguana.beans.Federacao#3
    at org.hibernate.ejb.event.EJB3DeleteEventListener.performDetachedEntityDeletionCheck(EJB3DeleteEventListener.java:67)
    at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:107)
    at org.hibernate.event.internal.DefaultDeleteEventListener.onDelete(DefaultDeleteEventListener.java:74)
    at org.hibernate.internal.SessionImpl.fireDelete(SessionImpl.java:946)
    at org.hibernate.internal.SessionImpl.delete(SessionImpl.java:925)
    at org.hibernate.ejb.AbstractEntityManagerImpl.remove(AbstractEntityManagerImpl.java:895)
    at br.com.iguana.dao.FederacaoDAO.removeFederacaoDoAluno(FederacaoDAO.java:69)
    at br.com.iguana.views.CadAluno.btnDeleteFederacaoActionPerformed(CadAluno.java:804)
    at br.com.iguana.views.CadAluno.access$700(CadAluno.java:43)
    at br.com.iguana.views.CadAluno$8.actionPerformed(CadAluno.java:669)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6527)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6292)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4883)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:719)
    at java.awt.EventQueue$4.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
    at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:184)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:229)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:227)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:227)
    at java.awt.Dialog.show(Dialog.java:1084)
    at java.awt.Component.show(Component.java:1656)
    at java.awt.Component.setVisible(Component.java:1608)
    at java.awt.Window.setVisible(Window.java:1014)
    at java.awt.Dialog.setVisible(Dialog.java:1005)
    at br.com.iguana.utils.AbreDialog.abreDialog(AbreDialog.java:20)
    at br.com.iguana.views.AlunoView.actionPerformed(AlunoView.java:186)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
    at java.awt.Component.processMouseEvent(Component.java:6527)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6292)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4883)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:719)
    at java.awt.EventQueue$4.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
    at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:184)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:229)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:227)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:227)
    at java.awt.Dialog.show(Dialog.java:1084)
    at java.awt.Component.show(Component.java:1656)
    at java.awt.Component.setVisible(Component.java:1608)
    at java.awt.Window.setVisible(Window.java:1014)
    at java.awt.Dialog.setVisible(Dialog.java:1005)
    at br.com.iguana.utils.AbreDialog.abreDialog(AbreDialog.java:20)
    at br.com.iguana.views.PrincipalView.panelAlunosMouseClicked(PrincipalView.java:231)
    at br.com.iguana.views.PrincipalView.access$200(PrincipalView.java:21)
    at br.com.iguana.views.PrincipalView$3.mouseClicked(PrincipalView.java:98)
    at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
    at java.awt.Component.processMouseEvent(Component.java:6530)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6292)
    at java.awt.Container.processEvent(Container.java:2234)
    at java.awt.Component.dispatchEventImpl(Component.java:4883)
    at java.awt.Container.dispatchEventImpl(Container.java:2292)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4542)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
    at java.awt.Container.dispatchEventImpl(Container.java:2278)
    at java.awt.Window.dispatchEventImpl(Window.java:2739)
    at java.awt.Component.dispatchEvent(Component.java:4705)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:719)
    at java.awt.EventQueue$4.run(EventQueue.java:717)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:109)
    at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:184)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:229)
    at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:227)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:227)
    at java.awt.Dialog.show(Dialog.java:1084)
    at java.awt.Component.show(Component.java:1656)
    at java.awt.Component.setVisible(Component.java:1608)
    at java.awt.Window.setVisible(Window.java:1014)
    at java.awt.Dialog.setVisible(Dialog.java:1005)
    at br.com.iguana.main.Main$1.run(Main.java:38)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:744)
    at java.awt.EventQueue.access$400(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:697)
    at java.awt.EventQueue$3.run(EventQueue.java:691)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:714)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
------------------------------------------------------------------------

Answer 1

I'm looking for how to delete a relationship of @ManyToMany.

事实证明CascacadeType.REMOVE您的关系映射中缺少:

public class Aluno {
    ...        
    //federacao
    @ManyToMany(cascade = {CascadeType.PERSIST
                         , CascadeType.MERGE
                         , CascadeType.REFRESH }) // CascadeType.REMOVE is missing here
    @JoinTable(name = "FederacaoAluno"
             , joinColumns = @JoinColumn(name = "id_aluno")
             , inverseJoinColumns = @JoinColumn(name = "id_federacao"))
    private List<Federacao> federacao;
    ...
}

如果你不告诉持久化提供者这种关系应该在级联模式下删除，那么你可能会得到 SQLException关于外键被侵犯。