Java:为什么我的对象实例有两个serialVersionUID？

Question

我正在使用 Glassfish 3.1.2.2、作为 JPA 提供程序的 eclipse-link 和 Java JDK-6u31。我的应用程序是 3 层的，其中有一个独立的 Swing 客户端，在客户端计算机上的自己的 JVM 上运行。通过 JNDI 查找和 @Remote 接口(interface)与 EJB 通信。

我有以下对象继承结构:

我的 super 类“文档”:

@Entity
@Table(name = "Document")
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public class Document implements IUpdateableEntity {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Long id;

    @Basic(optional=false, fetch=FetchType.LAZY)
    @Lob
    private byte[] content;

    @Transient
    private transient File file;

    public Document() { }

    // getters and setters ...

}

...和一个子类“发票”:

@Entity
@Table(name = "Dokument")
public class Invoice extends Document implements IUpdateableEntity {

    private static final long serialVersionUID = 1L;

    // some additional relations and attributes ...

    public Invoice () { }

    // getters and setters ...

}

现在，我在调用 ejb 外观以保留发票对象(调用 persist()、flush()、refresh() 并将对象返回给客户端以便为客户端提供自动生成的发票对象时遇到此异常ID):

29.11.2012 20:21:25 com.sun.corba.ee.spi.orbutil.logex.WrapperGenerator handleFullLogging
WARNUNG: IOP00810011: Exception from readValue on ValueHandler in CDRInputStream
org.omg.CORBA.MARSHAL: WARNUNG: IOP00810011: Exception from readValue on ValueHandler in CDRInputStream  vmcid: OMG  minor code: 11 completed: Maybe

我已经在互联网上进行了梳理，并发现了指向serialVersionUID问题的提示，因为在此示例中CORBA编码显然失败了。

然后，我在 Netbeans IDE 中打开调试器，并在将对象发送到服务器端 ejb bean 之前检查对象的状态。

在调试器窗口中打开“Static Fields”节点时，我意识到存在重复的serialVersionUID(与下图相比):

-有人知道如何解决这个问题吗？

我的项目中还有其他类似的继承结构，它们的构造非常相似(没有@Lob)，并且我在那里没有这个问题... @Lob 字段是否会以某种方式引发此行为？

非常感谢任何帮助并提前感谢您!

编辑:这是完整的堆栈跟踪:

29.11.2012 20:21:25 com.sun.corba.ee.spi.orbutil.logex.WrapperGenerator handleFullLogging
WARNUNG: IOP00810011: Exception from readValue on ValueHandler in CDRInputStream
org.omg.CORBA.MARSHAL: WARNUNG: IOP00810011: Exception from readValue on ValueHandler in CDRInputStream  vmcid: OMG  minor code: 11 completed: Maybe
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.sun.corba.ee.spi.orbutil.logex.corba.CorbaExtension.makeException(CorbaExtension.java:248)
    at com.sun.corba.ee.spi.orbutil.logex.corba.CorbaExtension.makeException(CorbaExtension.java:95)
    at com.sun.corba.ee.spi.orbutil.logex.WrapperGenerator.handleFullLogging(WrapperGenerator.java:387)
    at com.sun.corba.ee.spi.orbutil.logex.WrapperGenerator.access$400(WrapperGenerator.java:107)
    at com.sun.corba.ee.spi.orbutil.logex.WrapperGenerator$2.invoke(WrapperGenerator.java:511)
    at com.sun.corba.ee.spi.orbutil.proxy.CompositeInvocationHandlerImpl.invoke(CompositeInvocationHandlerImpl.java:99)
    at $Proxy24.valuehandlerReadException(Unknown Source)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.readRMIIIOPValueType(CDRInputStream_1_0.java:1022)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1123)
    at com.sun.corba.ee.impl.encoding.CDRInputObject.read_value(CDRInputObject.java:531)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:2162)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:2404)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1224)
    at com.sun.corba.ee.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:425)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:308)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:274)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.readRMIIIOPValueType(CDRInputStream_1_0.java:1015)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1123)
    at com.sun.corba.ee.impl.encoding.CDRInputObject.read_value(CDRInputObject.java:531)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:2162)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:2404)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1224)
    at com.sun.corba.ee.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:425)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:308)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:274)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.readRMIIIOPValueType(CDRInputStream_1_0.java:1015)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1123)
    at com.sun.corba.ee.impl.encoding.CDRInputObject.read_value(CDRInputObject.java:531)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:2162)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:2404)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1224)
    at com.sun.corba.ee.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:425)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:308)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:274)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.readRMIIIOPValueType(CDRInputStream_1_0.java:1015)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1123)
    at com.sun.corba.ee.impl.encoding.CDRInputObject.read_value(CDRInputObject.java:531)
    at com.sun.corba.ee.impl.presentation.rmi.ExceptionHandlerImpl$ExceptionRWRMIImpl.read(ExceptionHandlerImpl.java:180)
    at com.sun.corba.ee.impl.presentation.rmi.ExceptionHandlerImpl.readException(ExceptionHandlerImpl.java:290)
    at com.sun.corba.ee.impl.presentation.rmi.DynamicMethodMarshallerImpl.readException(DynamicMethodMarshallerImpl.java:502)
    at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:205)
    at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:152)
    at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:227)
    at ch.lawsuite.control.__DokumentFacadeRemote_Remote_DynamicStub.create(ch/lawsuite/control/__DokumentFacadeRemote_Remote_DynamicStub.java)
    at ch.lawsuite.control._DokumentFacadeRemote_Wrapper.create(ch/lawsuite/control/_DokumentFacadeRemote_Wrapper.java)
    at ch.lawsuite.gui.misc.unterlagen.ModDocumentUI.btnSpeichernActionPerformed(ModDocumentUI.java:631)
    at ch.lawsuite.gui.misc.unterlagen.ModDocumentUI.access$300(ModDocumentUI.java:52)
    at ch.lawsuite.gui.misc.unterlagen.ModDocumentUI$6.actionPerformed(ModDocumentUI.java:384)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6290)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6055)
    at java.awt.Container.processEvent(Container.java:2039)
    at java.awt.Component.dispatchEventImpl(Component.java:4653)
    at java.awt.Container.dispatchEventImpl(Container.java:2097)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4575)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4236)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4166)
    at java.awt.Container.dispatchEventImpl(Container.java:2083)
    at java.awt.Window.dispatchEventImpl(Window.java:2482)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
    at java.awt.EventQueue.access$000(EventQueue.java:84)
    at java.awt.EventQueue$1.run(EventQueue.java:607)
    at java.awt.EventQueue$1.run(EventQueue.java:605)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:621)
    at java.awt.EventQueue$2.run(EventQueue.java:619)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:178)
    at java.awt.Dialog$1.run(Dialog.java:1044)
    at java.awt.Dialog$3.run(Dialog.java:1096)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.Dialog.show(Dialog.java:1094)
    at java.awt.Component.show(Component.java:1584)
    at java.awt.Component.setVisible(Component.java:1536)
    at java.awt.Window.setVisible(Window.java:841)
    at java.awt.Dialog.setVisible(Dialog.java:984)
    at ch.lawsuite.gui.misc.unterlagen.ModDocumentUI.showFrame(ModDocumentUI.java:118)
    at ch.lawsuite.gui.dateneinheit.akte.AkteUI.btnImportFestplatteActionPerformed(AkteUI.java:5877)
    at ch.lawsuite.gui.dateneinheit.akte.AkteUI.access$3300(AkteUI.java:75)
    at ch.lawsuite.gui.dateneinheit.akte.AkteUI$126.actionPerformed(AkteUI.java:4170)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6290)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6055)
    at java.awt.Container.processEvent(Container.java:2039)
    at java.awt.Component.dispatchEventImpl(Component.java:4653)
    at java.awt.Container.dispatchEventImpl(Container.java:2097)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4575)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4236)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4166)
    at java.awt.Container.dispatchEventImpl(Container.java:2083)
    at java.awt.Window.dispatchEventImpl(Window.java:2482)
    at java.awt.Component.dispatchEvent(Component.java:4481)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
    at java.awt.EventQueue.access$000(EventQueue.java:84)
    at java.awt.EventQueue$1.run(EventQueue.java:607)
    at java.awt.EventQueue$1.run(EventQueue.java:605)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$2.run(EventQueue.java:621)
    at java.awt.EventQueue$2.run(EventQueue.java:619)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.NullPointerException
    at com.sun.corba.ee.impl.orbutil.ClassInfoCache$ClassInfo.<init>(ClassInfoCache.java:156)
    at com.sun.corba.ee.impl.orbutil.ClassInfoCache.get(ClassInfoCache.java:281)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.read_value(CDRInputStream_1_0.java:1097)
    at com.sun.corba.ee.impl.encoding.CDRInputObject.read_value(CDRInputObject.java:531)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObjectField(IIOPInputStream.java:2162)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputClassFields(IIOPInputStream.java:2404)
    at com.sun.corba.ee.impl.io.IIOPInputStream.inputObject(IIOPInputStream.java:1224)
    at com.sun.corba.ee.impl.io.IIOPInputStream.simpleReadObject(IIOPInputStream.java:425)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValueInternal(ValueHandlerImpl.java:308)
    at com.sun.corba.ee.impl.io.ValueHandlerImpl.readValue(ValueHandlerImpl.java:274)
    at com.sun.corba.ee.impl.encoding.CDRInputStream_1_0.readRMIIIOPValueType(CDRInputStream_1_0.java:1015)
    ... 121 more

Answer 1

static 字段属于该类。您有一个发票实例，它既是发票又是文档。因此，有两个名为 serialVersionUID 的相关静态字段:Document.serialVersionUID 和 Invoice.serialVersionUID。在正常使用中，您只会看到最上面的一个，因为父类(super class)被屏蔽了。更重要的是，因为它们是私有(private)，因此子类的访问是被禁止的。调试器不受可见性规则的约束，并且显然会向您显示两者。

这似乎很正常，并且在没有任何其他证据的情况下，可能不是问题的原因。

您可以通过将其中一个值更改为不同的值(例如 2)来仔细检查这一点，然后您应该在调试器中更清楚地看到不同的值。