android - 如何在 map 初始化之前询问是否启用了位置？

Question

如何在 map 初始化之前询问是否启用位置？ 如果我尝试请求 MapsActivity 的权限，它所做的只是退出应用程序，因为它未启用。 我尝试将其添加到将用户引导至 map 的 Activity 中。但除非启用位置，否则它仍然只是关闭 Activity 。

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


        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync((OnMapReadyCallback) this);
        setUpMap();

    }
    private void buildAlertMessageNoGps() {
        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("Your GPS seems to be disabled, do you want to enable it?")
                .setCancelable(false)
                .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                    public void onClick(@SuppressWarnings("unused") final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
                        startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                    }
                })
                .setNegativeButton("No", new DialogInterface.OnClickListener() {
                    public void onClick(final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
                        dialog.cancel();
                    }
                });
        final AlertDialog alert = builder.create();
        alert.show();
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMap();
    }

    private void setUpMap() {
        final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );

        if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
            buildAlertMessageNoGps();
        }

        new Thread(new Runnable() {
            public void run() {
                try {
                    retrieveAndAddCities();
                } catch (IOException e) {
                    Log.e(LOG_TAG, "Cannot retrive cities", e);
                    return;
                }
            }
        }).start();
    }

    protected void retrieveAndAddCities() throws IOException {
        HttpURLConnection conn = null;
        final StringBuilder json = new StringBuilder();
        try {
            // Connect to the web service
            URL url = new URL(SERVICE_URL);
            conn = (HttpURLConnection) url.openConnection();
            InputStreamReader in = new InputStreamReader(conn.getInputStream());

            // Read the JSON data into the StringBuilder
            int read;
            char[] buff = new char[1024];
            while ((read = in.read(buff)) != -1) {
                json.append(buff, 0, read);
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error connecting to service", e);
            throw new IOException("Error connecting to service", e);
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }
        runOnUiThread(new Runnable() {
            public void run() {
                try {
                    createMarkersFromJson(json.toString());
                } catch (JSONException e) {
                    Log.e(LOG_TAG, "Error processing JSON", e);
                }
            }
        });
    }

    Marker mClosestMarker;
    float mindist;

    @Override
    public void onMapReady(GoogleMap googleMap) {

        mMap = googleMap;
        if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this,
                    Manifest.permission.ACCESS_FINE_LOCATION)
                    == PackageManager.PERMISSION_GRANTED) {
                //Location Permission already granted
                buildGoogleApiClient();
                mMap.setMyLocationEnabled(true);
            } else {
            }
        } else {
            buildGoogleApiClient();
            mMap.setMyLocationEnabled(true);
        }
    }

    @Override
    public void onPause() {
        super.onPause();
        if (mGoogleApiClient != null) {
            LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
        }
    }

    void createMarkersFromJson(String json) throws JSONException {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, 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;
        }
        mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
                mGoogleApiClient);

        JSONArray jsonArray = new JSONArray(json);
        for (int i = 0; i < jsonArray.length(); i++) {
            JSONObject jsonObj = jsonArray.getJSONObject(i);
            double lat = jsonObj.getJSONArray("latlng").getDouble(0);
            double lon = jsonObj.getJSONArray("latlng").getDouble(1);
            final String address = jsonObj.getString("address");
            Marker currentMarker = mMap.addMarker(new MarkerOptions()
                    .title(jsonObj.getString("name"))
                    .snippet(Integer.toString(jsonObj.getInt("population"))).draggable(true)
                    .position(new LatLng(jsonObj.getJSONArray("latlng").getDouble(0), jsonObj.getJSONArray("latlng").getDouble(1)))
                    .icon(BitmapDescriptorFactory
                            .defaultMarker(BitmapDescriptorFactory.HUE_AZURE)));
            mMap.setOnMarkerClickListener(new GoogleMap.OnMarkerClickListener() {
                @Override
                public boolean onMarkerClick(final Marker marker) {
                    new AlertDialog.Builder(MapsActivity.this)
                            .setTitle("Call Local Distributor " + marker.getTitle())
                            .setMessage("Would you like to dial now ? ")
                            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                    Intent intent = new Intent(Intent.ACTION_DIAL);
                                    intent.setData(Uri.parse("tel:" + marker.getSnippet()));
                                    startActivity(intent);
                                }
                            })
                            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialogInterface, int i) {
                                }
                            })
                            .create()
                            .show();
                    return true;
                }
            });
            float[] distance = new float[1];
            Location.distanceBetween(mLastLocation.getLatitude(), mLastLocation.getLongitude(), lat, lon, distance);
            if (i == 0) {
                mindist = distance[0];
            } else if (mindist > distance[0]) {
                mindist = distance[0];
                mClosestMarker = currentMarker;
                Toast.makeText(getApplicationContext(),
                        mClosestMarker.getTitle(), Toast.LENGTH_LONG)
                        .show();
            }
        }
    }

    protected synchronized void buildGoogleApiClient() {
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        mGoogleApiClient.connect();
    }

    @Override
    public void onConnected(Bundle bundle) {

        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(100);
        mLocationRequest.setFastestInterval(100);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
        if (ContextCompat.checkSelfPermission(this,
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
        }

    }

    @Override
    public void onConnectionSuspended(int i) {
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        if (connectionResult.hasResolution()) {
            try {
                connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
            } catch (IntentSender.SendIntentException e) {
                e.printStackTrace();
            }
        } else {
            Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());
        }
    }

    @Override
    public void onLocationChanged(Location location) {

        mLastLocation = location;
        if (mCurrLocationMarker != null) {
            mCurrLocationMarker.remove();
        }
        LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
        currentLatitude = location.getLatitude();
        currentLongitude = location.getLongitude();
        MarkerOptions markerOptions = new MarkerOptions();
        markerOptions.position(latLng);
        markerOptions.title("Current Position");
        mCurrLocationMarker = mMap.addMarker(markerOptions);
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 5));
    }

}

我厌倦了在 OnCreate 中使用这个 fragment ，但如果位置被禁用，应用程序仍然无法启动。

LocationManager lm = (LocationManager) getSystemService(LOCATION_SERVICE);
    if(!lm.isProviderEnabled(LocationManager.GPS_PROVIDER) ||
            !lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
        // Build the alert dialog
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Location Services Not Active");
        builder.setMessage("Please enable Location Services and GPS");
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialogInterface, int i) {
                // Show location settings when the user acknowledges the alert dialog
                Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(intent);
            }
        });
        Dialog alertDialog = builder.create();
        alertDialog.setCanceledOnTouchOutside(false);
        alertDialog.show();
    }

Answer 1

下面是我用于我的应用程序的代码 fragment ，它工作正常，检查它是否也适用于你

int off = 0;

    try {
        off = Settings.Secure.getInt(getContentResolver(), Settings.Secure.LOCATION_MODE);
    } catch (Settings.SettingNotFoundException e) {
        e.printStackTrace();
    }
    if (off == 0) {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);

        builder.setTitle("GPS is not enbled.");
        builder.setMessage("To Get Your Current Location You have To Enable Gps \n Are Sure Want to go to seeting to Enable GPS?");

        builder.setPositiveButton("YES", new DialogInterface.OnClickListener() {

            public void onClick(DialogInterface dialog, int which) {
                // Do nothing but close the dialog
                Intent onGPS = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(onGPS);

                // Toast.makeText(MapsActivity.this, c_lat +","+c_long, Toast.LENGTH_SHORT).show();


            }
        });

        builder.setNegativeButton("NO", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                // Do nothing
                dialog.dismiss();
            }
        });

        AlertDialog alert = builder.create();
        alert.show();