我有一个IntentService，在onCreate中调用方法startforeground()，然后在创建IntentService时看到通知。但是，当IntentService被销毁（转到onDestroy）时，我可以在销毁服务后的几秒钟内看到通知。这是为什么？
这是IntentService的代码：

public class USFIntentService extends IntentService {

    private static final String TAG = "USFIntentService";

    private static final int USF_NOTIFICATION_ID = 262276;
    private static final String USF_NOTIFICATION_CHANNEL_ID = "USF_NOTIFICATION_CHANNEL";

    public USFIntentService() {
        super("USFIntentService");
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Log.i(TAG,"in onCreate");
        startUsfForegroundService();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i(TAG,"in onDestroy");
    }

    private void startUsfForegroundService() {
        // Define notification channel
        CharSequence name = getString(R.string.channel_name);
        String description = getString(R.string.channel_description);
        int importance = NotificationManager.IMPORTANCE_DEFAULT;
        NotificationChannel channel =
                new NotificationChannel(USF_NOTIFICATION_CHANNEL_ID, name, importance);
        channel.setDescription(description);
        NotificationManager notificationManager = getSystemService(NotificationManager.class);
        notificationManager.createNotificationChannel(channel);

        // Build notification to be used for the foreground service.
        Notification notification =
                new Notification.Builder(this, USF_NOTIFICATION_CHANNEL_ID)
                        .setContentTitle(getText(R.string.notification_title))
                        .setContentText(getText(R.string.notification_message))
                        .setSmallIcon(R.drawable.usf_notification_icon)
                        .build();

        // Set the service as a foreground service.
        startForeground(USF_NOTIFICATION_ID, notification);
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.i(TAG, "onHandleIntent");
        if (intent != null) {
            doStuff();
        }
        Log.i(TAG,"End of onHandleIntent");
    }

}

我这样称呼这项服务：

Intent startServiceIntent = new Intent(intent);
startServiceIntent.setComponent(new ComponentName(context, USFIntentService.class));
context.startForegroundService(startServiceIntent);