android - 如何在 Google API 下检查设备中是否启用了定位服务

Question

我是 Google Api 位置的新手。我实现了一个处理所有 Location 回调的类。现在它在位置服务打开时工作。但如果关闭，我创建了一个函数 LocationAlertDialog() 来处理这个错误。我不明白我应该在我的代码中在哪里给她打电话的问题，因为我不知道我在哪里检查 GPS 或网络提供商是否可用。

这是我的代码:

public class LocationTool implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener{
    private Fragment frag;
    private GoogleApiClient mGoogleApiClient;
    private LocationRequest mLocationRequest;
    private Location mLastLocation;
    private boolean mRequestingLocationUpdates;
    public OnLocationChangedListener delegate= null;

    public LocationTool (Fragment frag, OnLocationChangedListener onLocationChangedListener)
    {
        mRequestingLocationUpdates = true;
        delegate = onLocationChangedListener;
        this.frag = frag;
        buildGoogleApiClientAndCreateLocationRequest();
    }

    public boolean ismRequestingLocationUpdates() {
        return mRequestingLocationUpdates;
    }

    public LocationRequest getmLocationRequest() {
        return mLocationRequest;
    }

    public GoogleApiClient getmGoogleApiClient() {
        return mGoogleApiClient;
    }

    public Location getmLastLocation() {
        return mLastLocation;
    }

    public void setmLastLocation(Location mLastLocation) {
        this.mLastLocation = mLastLocation;
    }

    public void buildGoogleApiClientAndCreateLocationRequest() {

    if (checkPlayServices()) {
        buildGoogleApiClient();
        createLocationRequest();
    }
}

    private synchronized void buildGoogleApiClient() {

        mGoogleApiClient = new GoogleApiClient.Builder(frag.getActivity())
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        if (mGoogleApiClient!=null)
            Log.d("mGoogleApiClient!=null", "mGoogleApiClient!=null");
    }

    private void createLocationRequest() {
        mLocationRequest = new LocationRequest();
        mLocationRequest.setInterval(Constants.UPDATE_INTERVAL);
        mLocationRequest.setFastestInterval(Constants.FASTEST_INTERVAL);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest.setSmallestDisplacement(Constants.DISPLACEMENT);
    }

    public boolean checkPlayServices() {
        int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(frag.getActivity());
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
                GooglePlayServicesUtil.getErrorDialog(resultCode, frag.getActivity(), Constants.PLAY_SERVICES_RESOLUTION_REQUEST).show();
            } else {
                Toast.makeText(frag.getActivity().getApplicationContext(), "This device is not supported.", Toast.LENGTH_LONG).show();
                frag.getActivity().finish();
            }
            return false;
        }
        return true;
    }


    @Override
    public void onConnected(Bundle bundle) {

            // Gets the best and most recent location currently available,
            // which may be null in rare cases when a location is not available.
            Log.d("Connected", "Connected");

            if (mRequestingLocationUpdates) {
                delegate.startLocationUpdates();
                Log.d("startLocationUpdates", "startLocationUpdates");
            }

            this.setmLastLocation(LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient));
            if (mLastLocation != null) {
                Log.d("mLastLocation != null", "mLastLocation != null");
                delegate.updateUI();
            }
    }

    @Override
    public void onConnectionSuspended(int i) {
        mGoogleApiClient.connect();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.i(this.frag.getClass().toString(), "Connection failed: ConnectionResult.getErrorCode() = "
                + connectionResult.getErrorCode());
        Log.d("Location services is off","failed");
    }

    public void LocationAlertDialog() {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(frag.getActivity());
        alertDialog.setTitle("Location settings");
        alertDialog.setMessage("We cannot retrieve your location. Please click on Settings and make sure your Location services is enabled");
        alertDialog.setPositiveButton("Settings",
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Intent intent = new Intent(
                                Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                        frag.getActivity().startActivity(intent);
                    }
                });
        alertDialog.setNegativeButton("Cancel",
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        //tryLocating = false;
                        dialog.cancel();
                    }
                });
        alertDialog.show();
    }

    /**
     * this function get Longitude and Latitude coordinates and send back the real street address.
     * @param LATITUDE
     * @param LONGITUDE
     * @param ctx
     * @return
     */
    public String getCompleteAddressString(double LATITUDE, double LONGITUDE, Context ctx) {
        String strAdd = "";
        Geocoder geocoder = new Geocoder(ctx, Locale.getDefault());
        try {
            List<Address> addresses = geocoder.getFromLocation(LATITUDE, LONGITUDE, 1);
            if (addresses != null) {
                Address returnedAddress = addresses.get(0);
                StringBuilder strReturnedAddress = new StringBuilder("");

                for (int i = 0; i < returnedAddress.getMaxAddressLineIndex(); i++) {
                    strReturnedAddress.append(returnedAddress.getAddressLine(i)).append("\n");
                }
                strAdd = strReturnedAddress.toString();
                Log.w("My Current location address", "" + strReturnedAddress.toString());
            } else {
                Log.w("My Current location address", "No Address returned!");
            }
        } catch (Exception e) {
            e.printStackTrace();
            Log.w("My Current location address", "Can not get Address!");
        }
        return strAdd;
    }

    /**
     * this function convert real address to geographical coordinates.
     * @param strAddress -real address
     * @return LatLng object which contain the coordinates
     */
    public LatLng getLocationFromAddress(String strAddress) {
        Geocoder coder = new Geocoder(frag.getActivity());
        List<Address> address;
        LatLng p1 = null;

        try {
            address = coder.getFromLocationName(strAddress, 5);
            if (address == null) {
                return null;
            }
            Address location = address.get(0);
            location.getLatitude();
            location.getLongitude();
            p1 = new LatLng(location.getLatitude(), location.getLongitude() );
            Log.d("coordinates",p1.latitude+""+p1.longitude);

        } catch (Exception ex) {
            Log.d("Location Exception", "error converting address");
            ex.printStackTrace();
        }

        return p1;
    }
}

Answer 1

以下代码检查位置是否启用。如果未启用，它会显示警报对话框。

LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    try {
        gps_enabled = lm.isProviderEnabled(LocationManager.GPS_PROVIDER);
    }catch (Exception ex){}
    try{
        network_enabled = lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
    }catch (Exception ex){}
    if(!gps_enabled && !network_enabled){
        AlertDialog.Builder dialog = new AlertDialog.Builder(this);
        dialog.setMessage(getResources().getString(R.string.gps_network_not_enabled));
        dialog.setPositiveButton(getResources().getString(R.string.open_location_settings), new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface paramDialogInterface, int paramInt) {                 
                Intent myIntent = new Intent( Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                Startup.this.startActivity(myIntent);                    
            }
        });
        dialog.setNegativeButton(getString(R.string.Cancel), new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface paramDialogInterface, int paramInt) {
                // TODO Auto-generated method stub

            }
        });
        dialog.show();
    }