2020-02-14-Android跨进程通信Messenger

Messenger是跨进程的Handler消息机制。
实际上是对AIDL和Handler的封装。
服务端

public class MessengerServer extends Service {

    public static final int MSG_REPORT = 1;

    private static final String TAG = "MessengerServer";

    private Messenger mMessenger = null;
    private MessageHandler mHandler = null;
    private HandlerThread mThread = null;

    public MessengerServer() {
        mThread = new HandlerThread("MessengerThread");
        mHandler = new MessageHandler(mThread.getLooper());
        mMessenger = new Messenger(mHandler);
    }

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

    private class MessageHandler extends Handler {

        public MessageHandler(Looper looper) {
            super(looper);
        }

        @Override
        public void handleMessage(@NonNull Message msg) {
            switch (msg.what) {
                case MSG_REPORT:
                    String value = (String)msg.obj;
                    Log.d(TAG, "report " + value);
                    break;
                    default:
                        Log.d(TAG, "Msg received what=" + msg.what);
            }
        }
    }
}

客户端

public class MessengerClient {

    private static final String TAG = "MessengerServer";

    private Messenger mMessenger = null;

    public void bindService(Context context) {
        Intent intent = new Intent(context, MessengerServer.class);
        context.bindService(intent, new BindConnection(), Context.BIND_AUTO_CREATE);
    }

    public void report(String value) {
        Log.d(TAG, "report " + value);
        if (mMessenger != null) {
            Message msg = Message.obtain();
            msg.what = MessengerServer.MSG_REPORT;
            msg.obj = value;
            try {
                mMessenger.send(msg);
            } catch (RemoteException e) {
                Log.e(TAG, "Fail to send msg e=" + e);
            }
        }
    }

    private class BindConnection implements ServiceConnection {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mMessenger = new Messenger(service);
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {
            Log.d(TAG, "onServiceDisconnected");
        }
    }
}