从类android获取位置

Posted 2021-04-12

我正在寻找一个获得lat和long的位置的课程。我从片段调用此类，这将获得最佳提供程序并调用方法来获取位置var。我有这个变量位置，但是当我返回变量pos时，position为null;为什么？我传递这个变量？

var pos into方法没关系，但是当我返回时为null。

public class locationmng {
public Context context;
private FusedLocationProviderClient fusedLocationProviderClient;
Location position;


public locationmng(Context c){
    context=c;

}

public Location GetLoc()  {
    if(ContextCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {

        LocationManager lm = (LocationManager) 
        context.getSystemService(Context.LOCATION_SERVICE);
        Criteria criteria = new Criteria();
        String bestProvider = lm.getBestProvider(criteria, true);

        if (bestProvider.equals(LocationManager.NETWORK_PROVIDER)) {

            position = getcoarseposition();

            return position;
       } 

}

@SuppressLint("MissingPermission")
public  Location getcoarseposition() {
   final Location[] pos = new Location[1];
    fusedLocationProviderClient=
      LocationServices.getFusedLocationProviderClient(context);
    fusedLocationProviderClient.getLastLocation()
            .addOnSuccessListener((Activity) context, new 
               OnSuccessListener<Location>() {
                @Override
                public void onSuccess(Location location) {
                    if (location != null) {
                         pos[0] =location;
                    }else {
                        Log.i("locmng","not found loc ");
                    }

                }
            });

    Log.i("locationmanager6894","ho trovato "+ a[0].getLongitude()+ "lat: "+ a[0].getLatitude());

    return pos[0];

}

答案

您的位置在OnSuccessListener<Location>()，它不会立即拨打电话。因此，您设置了一个监听器，但只有在获得您的位置时才会调用它。那么，你需要做什么：在你的听众的GetLoc()方法中做onSuccess(Location location)中定义的所有逻辑。

另一答案

可能并非所有位置设置都满足。您应该使用SettingsClient类提示用户更改其位置设置。文档：https://developer.android.com/training/location/change-location-settings

基本上你必须：

• 创建位置请求

protected void createLocationRequest() {
    LocationRequest mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(10000);
    mLocationRequest.setFastestInterval(5000);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
}

• 获取当前位置设置

LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder();


SettingsClient client = LocationServices.getSettingsClient(this);
Task<LocationSettingsResponse> task = client.checkLocationSettings(builder.build());

• 添加任务完整侦听器以了解您的位置设置是否正常

task.addOnSuccessListener(this, new OnSuccessListener<LocationSettingsResponse>() {
    @Override
    public void onSuccess(LocationSettingsResponse locationSettingsResponse) {
        // All location settings are satisfied. The client can initialize
        // location requests here.
        // ...
    }
});

task.addOnFailureListener(this, new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception e) {
        if (e instanceof ResolvableApiException) {
            // Location settings are not satisfied, but this can be fixed
            // by showing the user a dialog.
            try {
                // Show the dialog by calling startResolutionForResult(),
                // and check the result in onActivityResult().
                ResolvableApiException resolvable = (ResolvableApiException) e;
                resolvable.startResolutionForResult(MainActivity.this,
                        REQUEST_CHECK_SETTINGS);
            } catch (IntentSender.SendIntentException sendEx) {
                // Ignore the error.
            }
        }
    }
});

完成这三个步骤后，您将能够获得用户位置