android - fusedLocationProviderClient.lastLocation.addOnSuccessListener 始终为空

Question

我刚刚更新了我的位置 API 以使用 FusedLocationProviderClient 但我遇到了这个问题，当我关闭和打开 GPS 时，我总是得到空位置:

val fusedLocationProviderClient =
                        LocationServices.getFusedLocationProviderClient(callingActivity)
            fusedLocationProviderClient.flushLocations()
            getLocationRequest()

            checkLocationSettings(callingActivity, turnOnGpsRequestCode, callback) {
                // Location settings successful
                fusedLocationProviderClient.lastLocation
                        .addOnSuccessListener(callingActivity) {
                            location ->
                            // Here location is always null
callback.onCallback(MenumyRadar.RadarStatus.SUCCESS, location)
                        }
                        .addOnFailureListener {
                            callback.onCallback(MenumyRadar.RadarStatus.ERROR_UNKNOWN, null)
                        }
            }

在我打开另一个使用位置的应用程序(如 Google map 或 Uber)之前，它不起作用。

多亏了这个答案，我有了一些线索 FusedLocationApi.getLastLocation always null

Google 的解释是:

fusedLocationClient.lastLocation .addOnSuccessListener { location : Location? -> // Got last known location. In some rare situations this can be null. }

The getLastLocation() method returns a Task that you can use to get a Location object with the latitude and longitude coordinates of a geographic location. The location object may be null in the following situations:

Location is turned off in the device settings. The result could be null even if the last location was previously retrieved because disabling location also clears the cache. The device never recorded its location, which could be the case of a new device or a device that has been restored to factory settings. Google Play services on the device has restarted, and there is no active Fused Location Provider client that has requested location after the services restarted. To avoid this situation you can create a new client and request location updates yourself. For more information, see Receiving Location Updates.

但是没有说怎么处理，怎么办？

Answer 1

我找到了一个解决方案，这是发生了什么，当位置为空时，这意味着位置缓存已被清除，关闭 GPS 时会发生这种情况，所以当我打开它时，没有最后一个位置可以获取，我这样做是这样的:

checkLocationSettings(callingActivity, turnOnGpsRequestCode, callback) {
                // Location settings successful
                mFusedLocationProviderClient!!.lastLocation
                        .addOnSuccessListener(callingActivity) {
                            location ->
                            if (location == null || location.accuracy > 100) {
                                mLocationCallback = object : LocationCallback() {
                                    override fun onLocationResult(locationResult: LocationResult?) {
                                        stopLocationUpdates()
                                        if (locationResult != null && locationResult.locations.isNotEmpty()) {
                                            val newLocation = locationResult.locations[0]
                                            callback.onCallback(Status.SUCCESS, newLocation)
                                        } else {
                                            callback.onCallback(Status.ERROR_LOCATION, null)
                                        }
                                    }
                                }

                                mFusedLocationProviderClient!!.requestLocationUpdates(getLocationRequest(),
                                        mLocationCallback, null)
                            } else {
                                callback.onCallback(Status.SUCCESS, location)
                            }
                        }
                        .addOnFailureListener {
                            callback.onCallback(Status.ERROR_UNKNOWN, null)
                        }
            }

当位置为空时，开始使用回调请求位置

mFusedLocationProviderClient!!.requestLocationUpdates(getLocationRequest(), mLocationCallback, null)

然后当回调被调用时，一个新的位置被获取并再次开始获取位置。

有时会出现打开GPS时位置不为空但精度不好，所以我也检查定位精度是否足够好(对我来说足够好是100米)