Class not found when unmarshalling & ProcessKiller: Process

本文处理Android 程序扫描u盘文件，当U盘拔出时导致应用被杀死问题

 ProcessKiller: Process com.xxx.xxx.xxx (23174) has open file /storage/usb0/xxx

问题原因

u盘拔出系统杀死持有U盘句柄的进程

解决方案

开启新的进程进行u盘操作

 <service android:name=".service.xxxService"
            android:process=":xxx"/>

@Override
public void onCreate() {
    super.onCreate();
    IncomingHandler incomingHandler = new IncomingHandler(this);
    mMessenger = new Messenger(incomingHandler);
}

@Nullable
@Override
public IBinder onBind(Intent intent) {
    return mMessenger.getBinder();
}

static class IncomingHandler extends Handler {
    WeakReference<xxx> serviceWeakReference;

    public IncomingHandler(xxx service){
        serviceWeakReference = new WeakReference<xxx>(service);
    }
    
    @Override
    public void handleMessage(@NotNull Message msg) {
          final Message clientMsg = Message.obtain(msg);
          Bundle bundle = new Bundle();
          bundle.putParcelableArrayList("result", xxxInfoList);  
          clientMsg.setData(bundle);
          try {
               clientMsg.replyTo.send(clientMsg);
          } catch (RemoteException e) {
               e.printStackTrace();
               Log.i(TAG, "clientMsg.replyTo send exception : " + e.getMessage());
         }
    }
    
}

Client

Message msg = Message.obtain(null, Constants.RUN, 0, 0);
msg.replyTo = clientMessage;
sendMsg2Service(msg);

private void startService() {
    Intent intent = new Intent(mContext, xxxService.class);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        mContext.startForegroundService(intent);
    } else {
        mContext.startService(intent);
    }
    mContext.bindService(intent, connection, Service.BIND_AUTO_CREATE);
}

private ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            mMessenger = new Messenger(iBinder);
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            mMessenger = null;
        }
    };

private void sendMsg2Service(Message message) {
    try {
        mMessenger.send(message);
    } catch (RemoteException e) {
        e.printStackTrace();
    }
}

private void init(){
    clientMessage = new Messenger(new ClientHandler(this));
}

static class ClientHandler extends Handler{
    WeakReference<xxx> serviceWeakReference;

    ClientHandler(xxx musicService){
        serviceWeakReference = new WeakReference<xxx>(musicService);
    }
    @Override
    public void handleMessage(@NonNull Message msg) {
         Bundle bundle = msg.getData();
         ArrayList<MusicInfo> xxx = bundle.getParcelableArrayList("result");
    }
}

发现问题

Class not found when unmarshalling

处理如下

bundle.setClassLoader(xxxservice.getClassLoader());

总结

• 使用Messenger实现跨进程通讯
• 处理跨进程parcel 解析问题
• Android classloader相关知识