android 多個activity 共用一套廣播BroadcastReceiver

public abstract class ParentActivity extends Activity {
    public static final String ACTION_1 = "com.example.action1";
    public static final String ACTION_2 = "com.example.action2";


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ACTION_1);
        intentFilter.addAction(ACTION_2);
        registerReceiver(receiver, intentFilter);
    }


    protected abstract void doAction1();


    protected abstract void doAction2(String arg);


    BroadcastReceiver receiver = new BroadcastReceiver() {


        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (action.equals(ACTION_1)) {
                doAction1();
            } else if (action.equals(ACTION_2)) {
                String arg = intent.getStringExtra("arg");
                doAction2(arg);
            }
        }
    };


    @Override
    protected void onDestroy() {
        unregisterReceiver(receiver);
        super.onDestroy();
    };
}