android - .getLastLocation() FusedLocationProviderClient 的位置数据为空

Question

我通过单击按钮在我的应用程序中获取与 FusedLocationProviderClient 的坐标以存储到数据库中。问题是，当我重新启动手机或模拟器时，.getLastLocation() 为 null，我必须再次单击我订购的按钮才能使其正常工作。如果 location from .lastKnownPosition() 的值为 null，是否有办法强制获取当前位置？

// Google fused location client for GPS position
private FusedLocationProviderClient flpc;
// Vars to store GPS info
public Double latitude, longitude;
public Float accuracy;


// Google Fused Client for location
public void getLocation() {
    // FusedLocationProviderClient
    flpc = LocationServices.getFusedLocationProviderClient(context);
    if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ......
        return;
    }

    // Get the latest position from device
    Task<Location> task = flpc.getLastLocation();

    task.addOnSuccessListener(new OnSuccessListener<Location>() {
        @Override
        public void onSuccess(Location location) {
            if(location!=null) {
                latitude = location.getLatitude();
                longitude = location.getLongitude();
                accuracy = location.getAccuracy();
            }
        }
    });
}

在我的按钮处理程序中，我调用 getLocation() 并使用纬度、经度和精度存储到数据库中。

感谢任何帮助!

Answer 1

当getLastLocation()为null时，需要发起LocationRequest

private LocationRequest locationRequest;
private LocationCallback locationCallback;

...

locationRequest = LocationRequest.create();
locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
locationRequest.setInterval(20 * 1000);
locationCallback = new LocationCallback() {
    @Override
    public void onLocationResult(LocationResult locationResult) {
        if (locationResult == null) {
            return;
        }
        for (Location location : locationResult.getLocations()) {
            if (location != null) {
                wayLatitude = location.getLatitude();
                wayLongitude = location.getLongitude();
                txtLocation.setText(String.format(Locale.US, "%s -- %s", wayLatitude, wayLongitude));
            }
        }
    }
};
mFusedLocationClient.requestLocationUpdates(locationRequest, locationCallback, Looper.getMainLooper())

如果您不需要持续更新，您可以在收到请求后将其删除。

mFusedLocationClient.removeLocationUpdates(locationCallback);

更多信息在这里:https://medium.com/@droidbyme/get-current-location-using-fusedlocationproviderclient-in-android-cb7ebf5ab88e