java - 在 MapFragment 中显示当前位置

Question

我有一个位置类，它在 MapFragment 上创建一个实例，并且根据创建 map 的 Activity ，将放置不同的标记。我还希望 map 显示手机当前位置的标记。

我假设我可以做这样的事情，但我无法弄清楚如何获取和更新手机当前坐标并将其分配给 myLocation。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_location);

MapFragment googleMap = (MapFragment) getFragmentManager().findFragmentById(R.id.map);
    googleMap.getMapAsync(this);

    }

    @Override
            public void onMapReady(GoogleMap nMap){

        if(MainMenu.bkSource == true) {
            LatLng bkLatLng = new LatLng(54.5816008, -5.9651271);
            LatLng myLocation = new LatLng(???);
            nMap.addMarker(new MarkerOptions().position(bkLatLng).title("Burger King, Boucher Road"));
            nMap.addMarker(new MarkerOptions().position(myLocation).title("You Are Here");
            nMap.moveCamera(CameraUpdateFactory.newLatLngZoom(bkLatLng, 15));
            nMap.animateCamera(CameraUpdateFactory.zoomTo(18.0f));
        }
        if(MainMenu.kfcSource == true){
            LatLng bkLatLng = new LatLng(54.5771914, -5.9620562);
            nMap.addMarker(new MarkerOptions().position(bkLatLng).title("KFC, Boucher Road"));
            nMap.moveCamera(CameraUpdateFactory.newLatLngZoom(bkLatLng, 15));
            nMap.animateCamera(CameraUpdateFactory.zoomTo(18.0f));
        }
        if(MainMenu.mcdSource == true){
            LatLng bkLatLng = new LatLng(54.5879486, -5.9580009);
            nMap.addMarker(new MarkerOptions().position(bkLatLng).title("McDonald's, Boucher Road"));
            nMap.moveCamera(CameraUpdateFactory.newLatLngZoom(bkLatLng, 15));
            nMap.animateCamera(CameraUpdateFactory.zoomTo(18.0f));
        }

    }

Answer 1

这是一个扩展SupportMapFragment的示例Fragment，启动时它将获取用户的当前位置，放置标记并放大:

public class MapFragment extends SupportMapFragment
    implements OnMapReadyCallback,
    GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener,
    LocationListener {

GoogleMap mGoogleMap;
SupportMapFragment mapFrag;
LocationRequest mLocationRequest;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;

@Override
public void onResume() {
    super.onResume();

    setUpMapIfNeeded();
}

private void setUpMapIfNeeded() {

    if (mGoogleMap == null) {
        getMapAsync(this);
    }
}
@Override
public void onPause() {
    super.onPause();

    //stop location updates when Activity is no longer active
    if (mGoogleApiClient != null) {
        LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
    }
}

@Override
public void onMapReady(GoogleMap googleMap)
{
    mGoogleMap=googleMap;
    mGoogleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

    //Initialize Google Play Services
    if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        if (ContextCompat.checkSelfPermission(getActivity(),
                Manifest.permission.ACCESS_FINE_LOCATION)
                == PackageManager.PERMISSION_GRANTED) {
            //Location Permission already granted
            buildGoogleApiClient();
            mGoogleMap.setMyLocationEnabled(true);
        } else {
            //Request Location Permission
            checkLocationPermission();
        }
    }
    else {
        buildGoogleApiClient();
        mGoogleMap.setMyLocationEnabled(true);
    }
}

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

@Override
public void onConnected(Bundle bundle) {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(1000);
    mLocationRequest.setFastestInterval(1000);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
    if (ContextCompat.checkSelfPermission(getActivity(),
            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) {}

@Override
public void onLocationChanged(Location location)
{
    mLastLocation = location;
    if (mCurrLocationMarker != null) {
        mCurrLocationMarker.remove();
    }

    //Place current location marker
    LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
    MarkerOptions markerOptions = new MarkerOptions();
    markerOptions.position(latLng);
    markerOptions.title("Current Position");
    markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
    mCurrLocationMarker = mGoogleMap.addMarker(markerOptions);

    //move map camera
    mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng,11));

}

public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
private void checkLocationPermission() {
    if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {

        // Should we show an explanation?
        if (ActivityCompat.shouldShowRequestPermissionRationale(getActivity(),
                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(getActivity())
                    .setTitle("Location Permission Needed")
                    .setMessage("This app needs the Location permission, please accept to use location functionality")
                    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialogInterface, int i) {
                            //Prompt the user once explanation has been shown
                            ActivityCompat.requestPermissions(getActivity(),
                                    new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
                                    MY_PERMISSIONS_REQUEST_LOCATION );
                        }
                    })
                    .create()
                    .show();


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

@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(getActivity(),
                        Manifest.permission.ACCESS_FINE_LOCATION)
                        == PackageManager.PERMISSION_GRANTED) {

                    if (mGoogleApiClient == null) {
                        buildGoogleApiClient();
                    }
                    mGoogleMap.setMyLocationEnabled(true);
                }

            } else {

                // permission denied, boo! Disable the
                // functionality that depends on this permission.
                Toast.makeText(getActivity(), "permission denied", Toast.LENGTH_LONG).show();
            }
            return;
        }

        // other 'case' lines to check for other
        // permissions this app might request
    }
}

}

由于位置权限请求需要经过 Activity，因此您需要将结果从 Activity 路由到 Fragment 的 onRequestPermissionsResult() 方法:

公共(public)类 MainActivity 扩展 AppCompatActivity {

MapFragment mapFragment;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    mapFragment = new MapFragment();

    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.add(R.id.mapframe, mapFragment);
    transaction.commit();
}

@Override
public void onRequestPermissionsResult(int requestCode,
                                       String permissions[], int[] grantResults) {
    if (requestCode == MapFragment.MY_PERMISSIONS_REQUEST_LOCATION){
        mapFragment.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }
    else {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}

}

布局仅包含 MapFragment 所在的 FrameLayout。

activity_main.xml: