附加需求如何分析，现有代码如何扩展

新需求：将行程实时显示在地图上
1.TirpManager的程序的入口，需要和外层打交道和交互
2.应该在TripManager增加一个接口，回调给上层

public class TripManager {

    private TripTracker mTracker;
    private TripSetting mSettings;
    private OnLocationChangedListener listener;

    public void startTrip() {
        mSettings = new TripSetting();
        mTracker = new TripTracker(mSettings);
        mTracker.setLocationChangedListener(listener);
        mTracker.startTracker();
    }


    public void stopTrip() {
        mTracker.stopTracker();
        mTracker = null;
    }

    public void setLocationChangedListener(OnLocationChangedListener listener) {
        this.listener = listener;
        if (mTracker != null) {
            mTracker.setLocationChangedListener(listener);
        }
    }

    public interface OnLocationChangedListener {
        void onLocationChangedListener(GpsTracker.GpsEntity location);
    }
}

 @Override
    public void onGpsChanged(GpsTracker.GpsEntity gpsEntity) {
        mtripWriter.onGpschanged(gpsEntity);
        mListener.onLocationChangedListener(gpsEntity);
    }

    @Override
    public void onSensorChanged(SensorTracker.SensorEntity sensorEntity) {
        mtripWriter.onSensorchanged(sensorEntity);
    }

    public void setLocationChangedListener(TripManager.OnLocationChangedListener listener) {
        this.mListener = listener;
    }