Question

我需要反序列化对象，但是当我使用readObject读取对象时，我得到了这样的异常：

Exception raised: java.lang.Enum; Incompatible class (SUID): 
java.lang.Enum: static final long serialVersionUID =0L; 
but expected java.lang.Enum: static final long serialVersionUID =0L;

以下是代码：

public static void restore3x(PersistentHistory h, DictManager dictManager) throws Exception{
        SharedPreferences prefs = tryToGuess(h.mContext);
        if (prefs == null) return;
        Log.e("shdd","Found history!");
        String history = prefs.getString("History", null);
        ObjectInputStream objIn = null;
        try {
            //prepare
            objIn = new ObjectInputStream(new ByteArrayInputStream(Base64.decode(history))) {
                @Override
                protected ObjectStreamClass readClassDescriptor() throws IOException, ClassNotFoundException {
                    ObjectStreamClass osc = super.readClassDescriptor();
                    if (osc.getName().contains("slovoed")) {
                        try {
                            Field f;
                            f = osc.getClass().getDeclaredField("svUID");
                            f.setAccessible(true);
                            Log.e("shdd","Setting serialVersionUID");
                            f.setLong(osc, serialVersionUID);
                            Log.e("shdd","Set ok");
                            f = osc.getClass().getDeclaredField("className");
                            f.setAccessible(true);
                            Log.e("shdd","Setting class name");
                            f.set(osc, WordItem.class.getName());
                            Log.e("shdd","Set ok");
                        } catch (Exception e) {
                        }
                    }
                    return osc;
                }
            };
            //add to DB
            Log.e("shdd","Getting items");
            Collection<WordItem3x> items = (Collection<WordItem3x>) objIn.readObject();
            Log.e("shdd","Got ok");
            if (items.isEmpty()) return;
            Log.e("shdd","List's not empty");
            long timeSeconds = System.currentTimeMillis()/1000;
            for (WordItem3x w : items) {
                if (w.getWord() == null || w.getWord().length() == 0 || w.getIndexList() == 0) continue;
                Log.e("shdd","Adding word");
                h.add(w.getWord(), w.getIndexList(), timeSeconds--);
            }
        } catch (Exception e) {
            Log.e("shdd","Exception raised: " + e.getMessage());
            throw e;
        } finally {
            try { if (objIn != null) objIn.close(); } catch (Exception e) {}
            //prefs.edit().remove("History").commit();
        }
    }

我不知道出了什么问题。也许有人见过这样的例外？

这是WordItem3x readObject方法：

private void readObject(java.io.ObjectInputStream in) throws IOException,
                ClassNotFoundException {
            Log.e("shdd", "Reading object");
            in.defaultReadObject();

            int val1 = in.readInt();
            int val2 = in.readInt();
            if (val1 != -1 && val2 != -1) {
                direction = new Direction(val1, val2);
            } else
                direction = null;

            val1 = in.readInt();
            if (val1 != -1)
                typeList = eWordListType.values()[val1];
            else
                typeList = null;
        }

但我可以看到它从未被召唤过。

Answer 1

（注意：没有显示序列化代码，并且大部分省略了WordItem3x实现）

根据代码，我可以做的最好的猜测是在readClassDescriptor中使用反射来修改serialVersionUID最终会导致修改枚举的serialVersionUID。从java规范中，所有枚举条目serialVersionUID应为0L。我敢打赌在某些时候你将枚举改为无0L。这是AOSP中的代码块：

// Check SUIDs, note all SUID for Enum is 0L
if (0L != classDesc.getSerialVersionUID() || 0L != superClass.getSerialVersionUID()) {
        throw new InvalidClassException(superClass.getName(),
                "Incompatible class (SUID): " + superClass + " but expected " + superClass);
}

在修改serialVersionUID

之前尝试打印出对象的名称

ObjectStreamClass osc = super.readClassDescriptor();
osc.getName(); // is this an enum????

反序列化期间的奇怪异常

1 个答案: