java - 在 Java 中查找不可序列化字段的好方法

Question

我有一个非常复杂的 Java 对象要序列化(几周前运行良好)。在此期间实现了很多之后，序列化现在无法抛出以下异常:

java.io.NotSerializableException: sun.java2d.SunGraphics2D

我已经检查了所有看起来相关的类，但在其中的任何类中都找不到包含 Graphics2D 类型(或类似类型，如 BufferedImage 等)的字段。正如我所看到的，问题也可能是我正在使用一个本身可序列化的类(来自库等)，但具有不可序列化类型 Graphics2D 的字段。

那么，我的问题是:是否有一种“好的”方法来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。

提前致谢

卢卡斯

附言。这是异常的完整堆栈跟踪:

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)

Answer 1

好吧，受到 Ben Lawry 的启发，但他没有提出实际的实现，我还编写了一个类爬虫程序，它可以找到“不可序列化的字段”，即非静态、非 transient 字段本身未实现 Serializable 接口(interface)或包含非静态、非 transient 且未实现 Serializable 接口(interface)的字段。

你可以在main方法的列表中添加几个要测试的类(见注释)。输出是这些类或任何引用类的字段列表，这些类不能按上述定义序列化(但是，它并不完全等于实际可序列化的字段，而是捕获后者的超集)；对于本身确实实现了 Serializable 接口(interface)的每个字段，给出了该字段类型中引用的字段列表，这导致该字段不可序列化(如果列表为空，则该字段本身不实现 Serializable 接口(interface))。

这是代码，希望对其他人也有帮助:

import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;

import javax.swing.JComponent;

public class Crawler {
    public static boolean crawlRecursively(Field field, HashSet<Class<?>> alreadyCrawled, HashMap<Field, HashSet<String>> badFields) {
        if (alreadyCrawled.contains(field.getType())) {
            return !badFields.keySet().contains(field);
        }

        alreadyCrawled.add(field.getType());

        if (Modifier.isStatic(field.getModifiers())
                || Modifier.isTransient(field.getModifiers())
                || field.getType().isPrimitive()) {
            return true;
        } else if (Serializable.class.isAssignableFrom(field.getType())) {
            boolean allGood = true;

            for (Field f : field.getType().getDeclaredFields()) {
                boolean isGood = crawlRecursively(f, alreadyCrawled, badFields);
                if (!isGood) {
                    if (!badFields.containsKey(field)) {
                        badFields.put(field, new HashSet<>());
                    }
                    badFields.get(field).add(f.getType().getSimpleName() + " " + f.getName());
                    allGood = false;
                }
            }

            return allGood;
        } else {
            if (!badFields.containsKey(field)) {
                badFields.put(field, new HashSet<>());
            }

            return false;
        }
    }

    public static HashMap<Field, HashSet<String>> initiateCrawling(Collection<Class<?>> roots) {
        HashMap<Field, HashSet<String>> badFields = new HashMap<>();

        for (Class<?> root : roots) {
            for (Field f : root.getDeclaredFields()) {
                crawlRecursively(f, new HashSet<>(), badFields);
            }
        }

        return badFields;
    }

    public static void main(String[] args) {
        LinkedList<Class<?>> roots = new LinkedList<>();
        roots.add(JComponent.class); // ADD YOUR CLASSES HERE.
        HashMap<Field, HashSet<String>> badFields = initiateCrawling(roots);

        if (badFields.keySet().size() == 0) {
            System.out.println("All fields are serializable (not having checked the given class(es) themselves).");
        } else {
            System.out.println("The following fields are not serializable in the class tree(s) given by " + roots + ":");
        }

        for (Field field : badFields.keySet()) {
            System.out.println("<UnSer> "
                    + field.getType().getSimpleName() + " " 
                    + field.getName() + " (" 
                    + field.getDeclaringClass().getName() + ") => " + badFields.get(field));
        }
    }
}

类 JComponent 的示例输出:

The following fields are not serializable in the class tree(s) given by [class javax.swing.JComponent]:
<UnSer> Border border (javax.swing.JComponent) => []
<UnSer> ComponentInputMap windowInputMap (javax.swing.JComponent) => [JComponent component]
<UnSer> VetoableChangeSupport vetoableChangeSupport (javax.swing.JComponent) => [VetoableChangeListenerMap map, Object source]
<UnSer> SingleSelectionModel selectionModel (javax.swing.JPopupMenu) => []
<UnSer> JPopupMenu popupMenu (javax.swing.JComponent) => [SingleSelectionModel selectionModel]
<UnSer> Object source (java.beans.VetoableChangeSupport) => []
<UnSer> VetoableChangeListenerMap map (java.beans.VetoableChangeSupport) => []
<UnSer> JComponent component (javax.swing.ComponentInputMap) => [VetoableChangeSupport vetoableChangeSupport, JPopupMenu popupMenu, Border border, InputVerifier inputVerifier]
<UnSer> InputVerifier inputVerifier (javax.swing.JComponent) => []