允许访问后立即获取当前位置工作

Question

我已在我的应用程序中成功实现了谷歌地图和当前位置。我面临的唯一问题是，一旦用户接受了权限并允许定位，就需要重新加载片段，然后才能实现当前定位。

我的位置类：

public class LocationFragment extends Fragment implements OnMapReadyCallback {
    private LocationViewModel locationViewModel;
    private GoogleMap gMap;
    private MapView mapView;
    private Location currentLocation;
    private int LOCATION_PERMISSION_REQUEST_CODE = 1234;




    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        locationViewModel = ViewModelProviders.of( this ).get( LocationViewModel.class );
        View view = inflater.inflate( R.layout.fragment_location_customer, container, false );

        return view;
    }


    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated( view, savedInstanceState );



        mapView = (MapView) view.findViewById( R.id.map );
        if (mapView != null)
        {
            mapView.onCreate( null );
            mapView.onResume();
            mapView.getMapAsync( this );

        }



    }

    @Override
    public void onMapReady(GoogleMap googleMap)
    {
        UiSettings uiSettings = googleMap.getUiSettings();

        gMap = googleMap;
        LatLng coffeys = new LatLng( 54.572720, -5.959151 );
        gMap.addMarker( new MarkerOptions().position( coffeys ).title( "Coffey's Butchers" ) );
        gMap.moveCamera( CameraUpdateFactory.newLatLngZoom( coffeys, 12 ) );
        uiSettings.setZoomControlsEnabled(true);
        enableLocation();
    }





    public void enableLocation()
    {
        int permissionCheck = ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION);
        if (permissionCheck != PackageManager.PERMISSION_GRANTED)
        {
            ActivityCompat.requestPermissions(getActivity(), new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, LOCATION_PERMISSION_REQUEST_CODE);
        }
        if(permissionCheck == PackageManager.PERMISSION_GRANTED)
        {
            gMap.setMyLocationEnabled( true );
            final LocationListener locationListener = new LocationListener() {
                @Override
                public void onLocationChanged(Location location) {
                    // GPS may be turned off
                    if (location == null)
                    {
                        return;
                    }

                    Double lat = location.getLatitude();
                    Double lng = location.getLongitude();

                    currentLocation = location;
                    Toast.makeText( getActivity(), "Updated Location: " + lat + lng, Toast.LENGTH_SHORT ).show();

                }
            };

        }
    }

}

一旦允许访问，是否有办法让当前位置工作。

Answer 1

使用requestPermissions() 而不是ActivityCompat.requestPermissions()，在您的片段中覆盖onRequestPermissionsResult()，并在获得权限的情况下运行依赖于该权限的代码。

检查这个问题：How to check permission in fragment

Answer 2

先决条件： EasyPermission 库

---

第 1 步： 在清单文件中添加此权限

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

---

第 2 步：

    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    //Create location callback when it's ready.
    createLocationCallback()

    //createing location request, how mant request would be requested.
    createLocationRequest()

    //Build check request location setting request
    buildLocationSettingsRequest()
    
    //FusedLocationApiClient which includes location 
    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this)
    //Location setting client
    mSettingsClient = LocationServices.getSettingsClient(this)

    //Check if you have ACCESS_FINE_LOCATION permission
    if (!EasyPermissions.hasPermissions(
            this@MainActivity,
            Manifest.permission.ACCESS_FINE_LOCATION)) {
        requestPermissionsRequired()
    }
    else{
        //If you have the permission we should check location is opened or not
        checkLocationIsTurnedOn()
    }
   
}

---

第 3 步： 创建需要在 onCreate()

中调用的函数

private fun requestPermissionsRequired() {
    EasyPermissions.requestPermissions(
        this,
        getString(R.string.location_is_required_msg),
        LOCATION_REQUEST,
        Manifest.permission.ACCESS_FINE_LOCATION
    )
}

private fun createLocationCallback() {
    //Here the location will be updated, when we could access the location we got result on this callback.
    mLocationCallback = object : LocationCallback() {
        override fun onLocationResult(locationResult: LocationResult) {
            super.onLocationResult(locationResult)
            mCurrentLocation = locationResult.lastLocation
        }
    }
}

private fun buildLocationSettingsRequest() {
    val builder = LocationSettingsRequest.Builder()
    builder.addLocationRequest(mLocationRequest!!)
    mLocationSettingsRequest = builder.build()
    builder.setAlwaysShow(true)
}

private fun createLocationRequest() {
    mLocationRequest = LocationRequest.create()
    mLocationRequest!!.interval = 0
    mLocationRequest!!.fastestInterval = 0
    mLocationRequest!!.numUpdates = 1
    mLocationRequest!!.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
}

public fun checkLocationIsTurnedOn() { // Begin by checking if the device has the necessary location settings.
    mSettingsClient!!.checkLocationSettings(mLocationSettingsRequest)
        .addOnSuccessListener(this) {
            Log.i(TAG, "All location settings are satisfied.")
            startLocationUpdates()
        }
        .addOnFailureListener(this) { e ->
            val statusCode = (e as ApiException).statusCode
            when (statusCode) {
                LocationSettingsStatusCodes.RESOLUTION_REQUIRED -> {
                    try {
                        val rae = e as ResolvableApiException
                        rae.startResolutionForResult(this@MainActivity, LOCATION_IS_OPENED_CODE)
                    } catch (sie: IntentSender.SendIntentException) {
                    }
                }
                LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE -> {
                    mRequestingLocationUpdates = false
                }
            }
        }
}

private fun startLocationUpdates() {
    mFusedLocationClient!!.requestLocationUpdates(
        mLocationRequest,
        mLocationCallback, null
    )
}

---

第 4 步：

确保位置已打开或用户接受打开位置后，在 onActivityResult() 中处理回调。

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    when (requestCode) {
        LOCATION_IS_OPENED_CODE -> {
            if (resultCode == AppCompatActivity.RESULT_OK) {
                Log.d(TAG, "Location result is OK")
            } else {
                activity?.finish()
            }
        }
}

---

第 5 步： 从 FusedClientApi 获取最后一个已知位置

override fun onMapReady(map: GoogleMap) {
    mMap = map
    mFusedLocationClient.lastLocation.addOnSuccessListener {
        if(it!=null){
            locateUserInMap(it)
        }
    }

}
   private fun locateUserInMap(location: Location) {
    showLocationSafetyInformation()
    if(mMap!=null){
        val currentLocation = LatLng(location.latitude,location.longitude )
        addMarker(currentLocation)
    }
}


private fun addMarker(currentLocation: LatLng) {
    val cameraUpdate = CameraUpdateFactory.newLatLng(currentLocation)
    mMap?.clear()
    mMap?.addMarker(
        MarkerOptions().position(currentLocation)
            .title("Current Location")
    )
    mMap?.moveCamera(cameraUpdate)
    mMap?.animateCamera(cameraUpdate)
    mMap?.setMinZoomPreference(14.0f);
}