Play 位置服务 getLastLocation 返回 null

我正在尝试聆听位置变化，但有时onLocationChanged回调永远不会被调用并且getLastLocation回报null，而谷歌地图始终运行完美。

Note

如果我重新启动设备，定位服务将仅工作约 2 天；之后我的应用程序和SDK 示例当 Google 地图仍然工作时，它就可以工作。

这是我的服务代码：

public class VisitService extends Service implements
        GooglePlayServicesClient.ConnectionCallbacks,
        GooglePlayServicesClient.OnConnectionFailedListener, 
        LocationListener {

    private final IBinder mBinder = new VisitBinder();


    // A request to connect to Location Services
    private LocationRequest mLocationRequest;

    // Stores the current instantiation of the location client in this object
    private LocationClient mLocationClient;


    private boolean mLocationServiceConnected = false;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        initLocation();
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public IBinder onBind(Intent intent) {
        initLocation();
        return mBinder;
    }

    public void startVisit() {
        if (!servicesConnected()) {
            listener.onVisitStartError();
            return;
        }

        if (mLocationServiceConnected) {
            if (isAcceptableLocation(mLocationClient.getLastLocation())) {
                Toast.makeText(this, "You have arrived!", Toast.LENGTH_LONG);
            } else {
                mVisitListener.onVisitStartError();
            }
        }    
    }

    private boolean isAcceptableLocation(Location location) {
        if (location == null) {
            Toast.makeText(this, "Location is null", Toast.LENGTH_LONG).show();
            return false;
        }

        return true;
    }


    private void initLocation() {

        if (mLocationRequest == null) {
            // Create a new global location parameters object
            mLocationRequest = LocationRequest.create();
            /*
             * Set the update interval
             */
            mLocationRequest
                    .setInterval(LocationUtils.UPDATE_INTERVAL_IN_MILLISECONDS);

            // Use high accuracy
            mLocationRequest
                    .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

            // Set the interval ceiling to one minute
            mLocationRequest
                    .setFastestInterval(LocationUtils.FAST_INTERVAL_CEILING_IN_MILLISECONDS);

        }

        if (mLocationClient == null) {
            mLocationClient = new LocationClient(this, this, this);
            mLocationClient.connect();
        }
    }

    /**
     * Verify that Google Play services is available before making a request.
     * 
     * @return true if Google Play services is available, otherwise false
     */
    private boolean servicesConnected() {

        // Check that Google Play services is available
        int resultCode = GooglePlayServicesUtil
                .isGooglePlayServicesAvailable(this);

        // If Google Play services is available
        if (ConnectionResult.SUCCESS == resultCode) {
            // In debug mode, log the status
            Log.d(LocationUtils.APPTAG,
                    getString(R.string.play_services_available));

            return true;
        } else {

            return false;
        }
    }

    public class VisitBinder extends Binder {
        public VisitService getService() {
            return VisitService.this;
        }
    }


    /**
     * In response to a request to start updates, send a request to Location
     * Services
     */
    private void startPeriodicUpdates() {

        mLocationClient.requestLocationUpdates(mLocationRequest, this);
        Toast.makeText(this, "Location Update Requested", Toast.LENGTH_LONG).show();
    }

    /**
     * In response to a request to stop updates, send a request to Location
     * Services
     */
    private void stopPeriodicUpdates() {
        mLocationClient.removeLocationUpdates(this);

    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.d(LocationUtils.APPTAG, "Location Services Connection faild");


    }

    @Override
    public void onConnected(Bundle bundle) {
        Log.d(LocationUtils.APPTAG, "Location Services Connected");
        mLocationServiceConnected = true;
        startPeriodicUpdates();
    }

    @Override
    public void onDisconnected() {
        mLocationServiceConnected = false;
    }

    @Override
    public void onLocationChanged(Location location) {
        Toast.makeText(this, "Location has been changed", Toast.LENGTH_LONG).show();
    }
}

安卓清单

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

首先，这是一个错误。我也面临这个问题。

您可以尝试一个简单的解决方法。

在尝试获取最后位置之前请求位置更新，即在尝试使用 getLastLocation() 查找最后位置之前请求位置更新；

就像：

LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria crta = new Criteria();
crta.setAccuracy(Criteria.ACCURACY_FINE);
crta.setAltitudeRequired(true);
crta.setBearingRequired(true);
crta.setCostAllowed(true);
crta.setPowerRequirement(Criteria.POWER_LOW); 
String provider = locationManager.getBestProvider(crta, true);
Log.d("","provider : "+provider);
// String provider = LocationManager.GPS_PROVIDER; 
locationManager.requestLocationUpdates(provider, 1000, 0, locationListener);
Location location = locationManager.getLastKnownLocation(provider); 

该实现基于LocationManager。请选择位置客户端。

希望能帮助到你！

UPDATE

在这里，您还可以使用 onLocationChanged() 方法，因为每次位置更改时它都会更新您，而 getLastLocation() 方法返回最知名的位置，该位置可能为 NULL。

根据文档，GetLastLocation() 方法在极少数情况下将返回 NULL。但这种情况也经常发生在我身上。

最新更新

伙计们，关于 GPS 只有一处更新：

首先我们需要利用GoogleApiClient反而LocationClient class.

其次我们需要实施GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener

第三，我们需要重写它onConnected() , onConnectionSuspended() and onConnectionFailed() method.

休息一下，你就可以出发了。

CHEERS!