專案裡之前一直用序列化的方式部署一些快取，今天在魅族MX5上發現反序列化快取內容失效了，報錯內容如下

java.io.EOFException
    at java.io.DataInputStream.readByte(DataInputStream.java:77)
    at java.io.ObjectInputStream.nextTC(ObjectInputStream.java:505)
    at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:752)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1983)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1940)
    at java.io.ObjectInputStream.readFieldValues(ObjectInputStream.java:1113)
    at java.io.ObjectInputStream.defaultReadObject(ObjectInputStream.java:454)
    at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1345)
    at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1242)
    at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1835)
    at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:761)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1983)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1940)
    at java.util.ArrayList.readObject(ArrayList.java:661)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at java.io.ObjectInputStream.readObjectForClass(ObjectInputStream.java:1330)
    at java.io.ObjectInputStream.readHierarchy(ObjectInputStream.java:1242)
    at java.io.ObjectInputStream.readNewObject(ObjectInputStream.java:1835)
    at java.io.ObjectInputStream.readNonPrimitiveContent(ObjectInputStream.java:761)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1983)
    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:1940)
    at com.imaginato.qravedconsumer.handler.bv.a(Unknown Source)
    at com.imaginato.qravedconsumer.handler.bv.a(Unknown Source)
    at com.imaginato.qravedconsumer.fragment.bl.a(Unknown Source)
    at com.imaginato.qravedconsumer.fragment.bl.doInBackground(Unknown Source)
    at android.os.AsyncTask$2.call(AsyncTask.java:292)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:818)

返序列化的程式碼如下：

 /**
     * 反序列化一個list
     * @param context
     * @param fileName
     * @param <T>
     * @return
     * @author Alex
     */
    public <T> List<T> getArrayListFromDisk(Context context, String fileName) {
        if (context == null) return null;
        ObjectInputStream ois = null;
        File file = context.getCacheDir();
        String path = file.getAbsolutePath().concat(fileName);
        File target = new File(path);
        if (!target.exists()) {
            Log.i("Alex","沒有找到檔案"+fileName);
            return null;
        }
        List<T> arrayList = null;
        synchronized (ArrayListLock) {
            try {
                ois = new ObjectInputStream(new FileInputStream(target));
                arrayList = (ArrayList<T>) ois.readObject();
                return arrayList;
            } catch (ClassNotFoundException e) {
                Log.i("Alex", "反序列失敗", e);
            } catch (IOException e) {
                Log.i("Alex", "反序列失敗2", e);//上面的報錯是這裡打出來的
            } finally {
                if (ois == null) return null;
                try {
                    ois.close();
                } catch (IOException e) {
                    Log.i("Alex", "反序列失敗3", e);
                }
                return arrayList;
            }
        }
    }
 

使用工作管理員強制關閉app的時候經常會出現這種情況

後來發現可能是由於序列化檔案損壞引起的，如果在一個執行緒裡對這個檔案執行寫入操作，而執行緒沒有正常的結束而被強行終止了，可能會導致當前操作的檔案損壞，所以導致問題的程式碼如下

@Override
    public void onDestroy() {
        Log.i("Alex", "fragment2的onStop執行");
        if (aveArrayListToDisk(getActivity(), CARDS_LIST, "/homeCards.tmp"))
            JLogUtils.i("Alex", "序列化卡片到硬碟成功");
        else Log.i("Alex", "序列化卡片失敗");
        super.onDestroy();
        Log.i("Alex", "fragment的onDestroy執行了！！！");
    }
 

這個bug得到的教訓是，耗時操作不要放在onDestroy()裡,onDestroy()可能不會被執行或者還沒等執行完app的程序就被終止了，這對IO操作是致命的。