在 Java 中查找不可序列化字段的好方法

A good way to find unserializable fields in Java(在 Java 中查找不可序列化字段的好方法)

问题描述

我有一个非常复杂的 Java 对象要序列化(几周前它运行良好).在同时实现了很多之后，序列化现在失败并抛出以下异常:

I have a quite complex Java object to serialize (which worked fine a couple of weeks ago). After having implemented a lot in the meantime, the serialization now fails throwing the following exception:

java.io.NotSerializableException: sun.java2d.SunGraphics2D

我检查了所有似乎相关的类，但在其中的任何一个中都找不到持有 Graphics2D 类型(或类似类型，如 BufferedImage 等)的字段.在我看来，问题也可能是我正在使用一个类(来自一个库左右)，它本身是可序列化的，但有一个不可序列化类型 Graphics2D 的字段.

I have inspected all classes which seemed relevant, but could not find a field in any of them holding a Graphics2D type (or a similar type such as BufferedImage or the like). As I see it, the problem could also be that I'm using a class (from a library or so) which itself is serializable, but has a field of the unserializable type Graphics2D.

所以，我的问题是:有没有一种好"的方法可以找到序列化失败的地方?检查所有类和所做的所有更改似乎几乎不可行.

So, my question is: is there a "good" way to find the place where the serialization fails? Inspecting all classes and all changes made seems to be hardly feasible.

提前谢谢你

卢卡斯

PS.这是异常的完整堆栈跟踪:

PS. Here is the full stack trace of the exception:

java.io.NotSerializableException: sun.java2d.SunGraphics2D
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
    at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
    at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
    at java.awt.Container.writeObject(Container.java:3697)
    at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
    at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
    at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
    at java.awt.Container.writeObject(Container.java:3697)
    at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
    at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
    at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
    at java.awt.Container.writeObject(Container.java:3697)
    at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
    at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
    at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
    at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
    at java.awt.Container.writeObject(Container.java:3697)
    at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at java.awt.Window.writeObject(Window.java:2943)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at java.awt.AWTEventMulticaster.save(AWTEventMulticaster.java:946)
    at java.awt.Window.writeObject(Window.java:2931)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at java.util.LinkedList.writeObject(LinkedList.java:1131)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
    at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
    at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
    at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
    at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
    at eas.simulation.SerializableSimulationState.save(SerializableSimulationState.java:121)
    at eas.plugins.standard.visualization.ControlPanel.actionPerformed(ControlPanel.java:202)
    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.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.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)

推荐答案

可以假定库类是正确可序列化的，即将所有不可序列化的字段声明为瞬态，因此不应该 成为错误的根源.

The library class can be assumed to be correctly serializable, i.e. to declare all non-serializable fields as transient, and therefore shouldn't be the source of the error.

如果您的代码使用 ContextedRuntimeExceptions，它们是上述规则的例外，因为它们引用的对象可能无法序列化，这是 在 Javadoc 中的 addContextValue() 和 setContextValue() 方法中注明.如果上下文值是问题所在，它将解释为什么可疑类在没有此类字段的情况下获得了对 Graphics2D 对象的引用.

If your code is using ContextedRuntimeExceptions, they are an exception to the above rule because the objects they reference may not be serializable, and this is noted in the Javadoc at the methods addContextValue() and setContextValue(). If context values are the problem, it would explain why the suspect classes got a reference to a Graphics2D object without having such a field.

我在为 SunGraphics2D 复制 NotSerializableException 的过程中取得了有限的成功，但没有留下一个名称中带有Graphics"的明显字段，这可能是由于对更简单的类结构进行了测试.我发现除了上下文异常之外，集合是一个很好的怀疑对象，但前提是它们使用原始类型.如果集合有时仅填充图形，也可能导致间歇性故障.

I have had limited success replicating NotSerializableException for SunGraphics2D without leaving an obvious field with "Graphics" in its name laying around, which could be due to testing on a simpler class structure. I found that in addition to contexted exceptions, collections were a good suspect but only if they used raw types. Collections could also cause intermittent failures if they were only sometimes populated with Graphics.

根据您的应用，Ben Lawry 对类似问题的自动化解决方案 可能比手动搜索上述内容更容易实现.如果这条路行得通，它也可能会更彻底.你能得到堆栈跟踪吗?

Depending on your application, Ben Lawry's automated solution to a similar issue may be easier to implement than manually hunting for the above. If that path works, it will likely be more thorough as well. Can you get a stack trace?

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