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我嘗試用Hibernate的merge（）方法保存對象樹。實體Auftrag（表示「英文訂單」）包含一組Auftragsposition對象，與cascade="all-delete-orphan映射。Hibernate 3.6.6.Final（JBoss 6.1）merge（）瞬態對象樹
持久化發生在通過RMI調用的無狀態會話bean中。該方法打開一個新的（乾淨的）Session實例。當已經存在的訂單被保存時，merge（）會嘗試從數據庫中加載實體，然後將剛加載的相關訂單位置與會話的持久性上下文相關聯。稍後，當merge（）操作級聯到訂單頭寸時，會發生NonUniqueObjectException異常（因爲瞬態順序位置與Hibernate加載的位置不同）。
saveOrUpdate（）會得到類似的結果。
是否存在智能（儘可能少的代碼行）解決方案？或者需要解決這個問題，例如通過遞歸遍歷對象樹並保存（如與會話相關的）第一個瞬態對象？ （PS：我現在得到這個異常是因爲我把一個名爲AuftragEntityPersister的舊的，自定義的子類拋棄了 - 它從數據庫中清除了整個對象樹，然後再次插入這些東西，可能是爲了解決這個問題。）
參考異常堆棧跟蹤：
13:54:16,052 ERROR [de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean] Rolling back due to Hibernate-Exception: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [de.redacted.domain.auftrag.Auftragsposition#[email protected]0000]
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:190) [:3.6.6.Final]
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:143) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.saveTransientEntity(DefaultMergeEventListener.java:415) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.mergeTransientEntity(DefaultMergeEventListener.java:341) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:303) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:258) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:877) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:859) [:3.6.6.Final]
at org.hibernate.engine.CascadingAction$6.cascade(CascadingAction.java:279) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:425) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:362) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:338) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204) [:3.6.6.Final]
at org.hibernate.engine.Cascade.cascade(Cascade.java:161) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:630) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:490) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:255) [:3.6.6.Final]
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:84) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:867) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:851) [:3.6.6.Final]
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:855) [:3.6.6.Final]
at de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean.saveAuftrag(AuftragPersistenceSessionBean.java:1145) [:]
at de.redacted.services.persistence.auftrag.AuftragPersistenceSessionBean.saveAuftrag(AuftragPersistenceSessionBean.java:873) [:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_21]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_21]
at org.jboss.invocation.Invocation.performCall(Invocation.java:386) [:6.1.0.Final]
at org.jboss.ejb.StatelessSessionContainer$ContainerInterceptor.invoke(StatelessSessionContainer.java:233) [:6.1.0.Final]
at org.jboss.resource.connectionmanager.CachedConnectionInterceptor.invoke(CachedConnectionInterceptor.java:156) [:6.1.0.Final]
at org.jboss.ejb.plugins.StatelessSessionInstanceInterceptor.invoke(StatelessSessionInstanceInterceptor.java:173) [:6.1.0.Final]
at org.jboss.ejb.plugins.CallValidationInterceptor.invoke(CallValidationInterceptor.java:63) [:6.1.0.Final]
at org.jboss.ejb.plugins.AbstractTxInterceptor.invokeNext(AbstractTxInterceptor.java:121) [:6.1.0.Final]
at org.jboss.ejb.plugins.TxInterceptorCMT.runWithTransactions(TxInterceptorCMT.java:350) [:6.1.0.Final]
at org.jboss.ejb.plugins.TxInterceptorCMT.invoke(TxInterceptorCMT.java:181) [:6.1.0.Final]
at org.jboss.ejb.plugins.SecurityInterceptor.process(SecurityInterceptor.java:228) [:6.1.0.Final]
at org.jboss.ejb.plugins.SecurityInterceptor.invoke(SecurityInterceptor.java:211) [:6.1.0.Final]
at org.jboss.ejb.plugins.security.PreSecurityInterceptor.process(PreSecurityInterceptor.java:100) [:6.1.0.Final]
at org.jboss.ejb.plugins.security.PreSecurityInterceptor.invoke(PreSecurityInterceptor.java:84) [:6.1.0.Final]
at org.jboss.ejb.plugins.LogInterceptor.invoke(LogInterceptor.java:205) [:6.1.0.Final]
at org.jboss.ejb.plugins.ProxyFactoryFinderInterceptor.invoke(ProxyFactoryFinderInterceptor.java:138) [:6.1.0.Final]
at org.jboss.ejb.SessionContainer.internalInvoke(SessionContainer.java:650) [:6.1.0.Final]
at org.jboss.ejb.Container.invoke(Container.java:1072) [:6.1.0.Final]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_21]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_21]
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157) [:6.0.0.GA]
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96) [:6.0.0.GA]
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88) [:6.0.0.GA]
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:271) [:6.0.0.GA]
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:670) [:6.0.0.GA]
at org.jboss.invocation.unified.server.UnifiedInvoker.invoke(UnifiedInvoker.java:232) [:6.1.0.Final]
at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:967) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.completeInvocation(ServerThread.java:791) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:744) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:586) [:6.1.0.Final]
at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:234) [:6.1.0.Final]