我在我的应用程序中有以下流程在后台运行：

OneTimeWorkRequest启动JobIntentService ，而后者又在onHandleWork()方法中调用runService() (我的方法)。

private void runService(final Context ctx, final IndoorOutdoorManager.AggregatedDetectionListener detectionListener, long mode, long requestedTimeout, final int trigger) {

this.acquireWakeLock();

// Get the requested manager's timeout.

long managerTimeout = (requestedTimeout < TIMEOUT_SERVICE_MAX) ? requestedTimeout : TIMEOUT_SERVICE_MAX;

long tick = (managerTimeout == DETECTION_SHORT) ? TICK_SHORT : TICK_LOOP;

// Guard the service with a countdown timer.

if (countDownTimer != null) {

countDownTimer.cancel();

}

countDownTimer = new CountDownTimer(managerTimeout, tick) {

@Override

public void onTick(long millisUntilFinished) { }

@Override

public void onFinish() {

IndoorOutdoorLogger.d(IndoorOutdoorService.this, TAG, "Timeout reached");

if (countDownTimer != null) {

countDownTimer.cancel();

}

IndoorOutdoorService.this.stopSelf();

IndoorOutdoorLogger.d(IndoorOutdoorService.this, TAG, "Indoor Outdoor Service shut down.");

}

}.start();

if (mode != 0) {

isInLoopMode.set(mode == DETECTION_LOOP);

Thread t = new Thread() {

public void run() {

synchronized (lock) {

if (manager == null) {

manager = new IndoorOutdoorManager(ctx, detectionListener, isInLoopMode.get(), trigger);

}

if (client == null) {

client = new IndoorOutdoorClient(ctx, null);

}

manager.start();

client.startUserActivityRealTimeUpdates();

}

}

};

t.start();

}

}

当我尝试运行应用程序时，我得到以下异常：

Can't create handler inside thread that has not called Looper.prepare()

异常指向的行是我创建countDownTimer实例的地方。

几点注意事项：如果是Android N和流量下面是：广播接收器开始onStartCommand()一个的Service这反过来会运行我runService()方法，没有任何问题，即使是在研究背景。 要调整应用程序以在Android O及更高版本上运行，我必须使用WorkManager并将服务更改为JobIntentService以支持后台运行。 它导致CountDownTimer异常，现在我被卡住了。