如何访问片段中的当前位置？

Question

我想以片段的形式访问我当前的位置。我写了这个程序。代码中没有错误，但它只显示谷歌地图；它不显示我当前的位置和标记。

我在从 manifest 和 getApplicationContext 访问权限时感到困惑，因为我在那里使用 getActivty() 而不是 this，因为它给了我错误。

我的代码有什么问题？

void locationTracker() {
    SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    locationManager = (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
    if ((ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) && (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)) {
        // TODO: Consider calling
        //    ActivityCompat#requestPermissions
        // here to request the missing permissions, and then overriding
        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
        //                                          int[] grantResults)
        // to handle the case where the user grants the permission. See the documentation
        // for ActivityCompat#requestPermissions for more details.
        return;
    }

    if (locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, new LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                double latitude = location.getLatitude();
                double longitude = location.getLongitude();
                LatLng latLng= new LatLng(latitude,longitude);
                Geocoder geocoder=new Geocoder(getActivity().getApplicationContext());
                try {
                    List<Address> addressList = geocoder.getFromLocation(latitude,longitude,1);
                    String str = addressList.get(0).getLocality()+",";
                    str+= addressList.get(0).getCountryName();
                    mMap.addMarker(new MarkerOptions().position(latLng).title(str));
                    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
                } catch (IOException e) {
                    e.printStackTrace();
                }


            }

            @Override
            public void onStatusChanged(String provider, int status, Bundle extras) {

            }

            @Override
            public void onProviderEnabled(String provider) {

            }

            @Override
            public void onProviderDisabled(String provider) {

            }
        });
    } else if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, new LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                double latitude = location.getLatitude();
                double longitude = location.getLongitude();
                LatLng latLng= new LatLng(latitude,longitude);
                Geocoder geocoder=new Geocoder(getActivity().getApplicationContext());
                try {
                    List<Address> addressList = geocoder.getFromLocation(latitude,longitude,1);
                    String str = addressList.get(0).getLocality()+",";
                    str+= addressList.get(0).getCountryName();
                    mMap.addMarker(new MarkerOptions().position(latLng).title(str));
                    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
                } catch (IOException e) {
                    e.printStackTrace();
                }


            }

            @Override
            public void onStatusChanged(String provider, int status, Bundle extras) {

            }

            @Override
            public void onProviderEnabled(String provider) {

            }

            @Override
            public void onProviderDisabled(String provider) {

            }
        });
    }
}

Answer 1

1-如果您的android>23，请确保在运行时询问位置的权限

2-GPS 在室内不起作用。

使用此代码在运行时询问位置权限

   public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;

public boolean checkLocationPermission() {
    if (ContextCompat.checkSelfPermission(this,
            Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {

        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(this,
                Manifest.permission.ACCESS_FINE_LOCATION)) {

            // Show an explanation to the user *asynchronously* -- don't block
            // this thread waiting for the user's response! After the user
            // sees the explanation, try again to request the permission.
            new AlertDialog.Builder(this)
                    .setTitle(R.string.title_location_permission)
                    .setMessage(R.string.text_location_permission)
                    .setPositiveButton(R.string.ok, new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            //Prompt the user once explanation has been shown
                            ActivityCompat.requestPermissions(MainActivity.this,
                                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                                    MY_PERMISSIONS_REQUEST_LOCATION);
                        }
                    })
                    .create()
                    .show();


        } else {
            // No explanation needed, we can request the permission.
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                    MY_PERMISSIONS_REQUEST_LOCATION);
        }
        return false;
    } else {
        return true;
    }
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSIONS_REQUEST_LOCATION: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0
                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                // permission was granted, yay! Do the
                // location-related task you need to do.
                if (ContextCompat.checkSelfPermission(this,
                        Manifest.permission.ACCESS_FINE_LOCATION)
                        == PackageManager.PERMISSION_GRANTED) {

                    //Request location updates:
                    locationManager.requestLocationUpdates(provider, 400, 1, this);
                }

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.

            }
            return;
        }

    }
}



Then call the checkLocationPermission() method in onCreate():





@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //.........

        checkLocationPermission();
    }

然后您可以完全按照问题中的方式使用 onResume() 和 onPause()。

这里是精简版，简洁一些：

 @Override
    protected void onResume() {
        super.onResume();
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {

            locationManager.requestLocationUpdates(provider, 400, 1, this);
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {

            locationManager.removeUpdates(this);
        }
    }

不要忘记将其添加到清单中

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