Question

我必须安排工作以获取用户当前位置并以给定的时间间隔更新到服务器（即使该应用未运行）。

我正在尝试WorkManagerAPI来实现功能。是否可以通过doWork()方法获取用户的当前位置？

locationManager.requestLocationUpdates(
    provider, timeInterval, travelDistance, locationListener
);

当我从doWork()请求位置更新时，抛出以下错误。

java.lang.RuntimeException：无法在尚未调用Looper.prepare（）的线程内创建处理程序。

Answer 1

据我了解，在Worker线程上实现LocationManager.requestLocationUpdates（）时，调用是在WorkManager创建的非UI后台线程上进行的。 LocationManager.requestLocationUpdates（）是一个异步调用，可能在另一个后台线程上。要处理LocationListener定义的回调，调用线程必须保持活动状态。这就是为什么该异常显示为

无法在尚未调用Looper.prepare（）的线程内创建处理程序。

检查下面的代码段。请将此视为伪代码，我尚未测试过这段代码。

public class LocationWorker extends Worker {

    String LOG_TAG = "LocationWorker";
    private Context mContext;
    private MyHandlerThread mHandlerThread;

    public LocationWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
        super(context, workerParams);
        mContext = context;
    }

    @NonNull
    @Override
    public Result doWork() {
        Log.d(LOG_TAG, "doWork");

        mHandlerThread = new MyHandlerThread("MY_THREAD");
        mHandlerThread.start();

        Runnable runnable = new Runnable() {
            @Override
            public void run() {

                LocationManager locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
                String bestProvider = locationManager.getBestProvider(new Criteria(), true);

                boolean permission = false;
                if (PermissionChecker.checkSelfPermission(mContext, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED &&
                        PermissionChecker.checkSelfPermission(mContext, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
                    Log.e(LOG_TAG, "This app requires ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION permissions.");
                    permission = true;
                }

                Log.d(LOG_TAG, "permission: "+permission);
                Log.d(LOG_TAG, "bestProvider: "+bestProvider);

                if (permission && bestProvider != null) {

                    MyLocationListener locListener = new MyLocationListener();
                    locationManager.requestLocationUpdates(bestProvider, 500, 1, locListener, mHandlerThread.getLooper());
                }
            }
        };

        mHandlerThread.post(runnable);

        return Result.success();
    }


    class MyHandlerThread extends HandlerThread {

        Handler mHandler;

        MyHandlerThread(String name) {
            super(name);
        }

        @Override
        protected void onLooperPrepared() {
            Looper looper = getLooper();
            if (looper != null)
                mHandler = new Handler(looper);
        }

        void post(Runnable runnable) {
            if (mHandler != null)
                mHandler.post(runnable);
        }
    }

    class MyLocationListener implements LocationListener
    {
        @Override
        public void onLocationChanged(final Location loc)
        {
            Log.d(LOG_TAG, "Location changed: " + loc.getLatitude() +","+ loc.getLongitude());
        }

        @Override
        public void onStatusChanged(String provider, int status, Bundle extras)
        {
            Log.d(LOG_TAG, "onStatusChanged");
        }

        @Override
        public void onProviderDisabled(String provider)
        {
            Log.d(LOG_TAG, "onProviderDisabled");
        }

        @Override
        public void onProviderEnabled(String provider)
        {
            Log.d(LOG_TAG, "onProviderEnabled");
        }
    }
}

是否可以从Worker类中获取用户位置？

1 个答案: