如何使用Google Maps android API v2获取我的位置更改事件？

Question

如何使用Google Maps android API v2获取我的位置更改事件？

在v1中,您可以执行下一步操作以处理位置更改事件:

public class MyLocationOverlay extends com.google.android.maps.MyLocationOverlay {

    /**
     * Listener
     */
    public interface Listener {
        void onLocationChanged(android.location.Location location);
    }

    private Listener listener;

    public MyLocationOverlay(Context context, MapView mapView, Listener listener) {
        super(context, mapView);

        this.listener = listener;
    }

    @Override
    public synchronized void onLocationChanged(Location location) {
        super.onLocationChanged(location);

        // fire listener
        if (listener != null)
            listener.onLocationChanged(location);
    }
}

Answer 1

更新:谷歌推出了新的LocationClient和相关的LocationListener(该OnMyLocationChangeListener界面现已弃用).

您可以通过LocationSource为my-location图层创建自定义来完成此操作.下面是一个自动将相机置于当前位置("我的位置")中心的示例,类似于MyLocationOverlayGoogle Maps Android API v1中提供的功能.

所以你可以简单地替换这行代码

mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));

使用位置更改时需要执行的任何功能.

public class PlaceMapFragment extends SupportMapFragment {

    // Note that this may be null if the Google Play services APK is not available.
    private GoogleMap mMap;

    protected PlaceActivity activity;
    private FollowMeLocationSource followMeLocationSource;
    private Context mContext;

    /* We need the Context in order to get a reference to the Location Manager
     * (when instantiating this fragment from your activity use:
     *  PlaceMapFragment mapFragment = new PlaceMapFragment(this); ) */
    public PlaceMapFragment(Context context) {
        this.mContext = context;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        activity = (PlaceActivity)getActivity();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // creates our custom LocationSource and initializes some of its members
        followMeLocationSource = new FollowMeLocationSource();

        /* We can't be guaranteed that the map is available because Google Play services might not be available.
         * (un-comment the following line when using this code in a FragmentActivity / Activity 
         *  to try get a reference to the map here !) */
        //setUpMapIfNeeded();
    }

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

        /* We query for the best Location Provider everytime this fragment is displayed
         * just in case a better provider might have become available since we last displayed it */
        followMeLocationSource.getBestAvailableProvider();

        // Get a reference to the map/GoogleMap object
        setUpMapIfNeeded();

        /* Enable the my-location layer (this causes our LocationSource to be automatically activated.)
         * While enabled, the my-location layer continuously draws an indication of a user's
         * current location and bearing, and displays UI controls that allow a user to interact
         * with their location (for example, to enable or disable camera tracking of their location and bearing).*/
        mMap.setMyLocationEnabled(true);
    }

    @Override
    public void onPause() {
        /* Disable the my-location layer (this causes our LocationSource to be automatically deactivated.) */
        mMap.setMyLocationEnabled(false);

        super.onPause();
    }

    /**
     * Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
     * installed) and the map has not already been instantiated. This will ensure that we only ever
     * manipulate the map once when it {@link #mMap} is not null.
     * <p>
     * If it isn't installed {@link SupportMapFragment} (and {@link com.google.android.gms.maps.MapView
     * MapView}) will show a prompt for the user to install/update the Google Play services APK on their device.
     */
    private void setUpMapIfNeeded() {
        // Do a null check to confirm that we have not already instantiated the map.
        if (mMap == null) {
            mMap = getMap();
            // Check if we were successful in obtaining the map.
            if (mMap != null) {
                // The Map is verified. It is now safe to manipulate the map:

                // Replace the (default) location source of the my-location layer with our custom LocationSource
                mMap.setLocationSource(followMeLocationSource);

                // Set default zoom
                mMap.moveCamera(CameraUpdateFactory.zoomTo(15f));
            }
        }
    }

    /* Our custom LocationSource. 
     * We register this class to receive location updates from the Location Manager
     * and for that reason we need to also implement the LocationListener interface. */
    private class FollowMeLocationSource implements LocationSource, LocationListener {

        private OnLocationChangedListener mListener;
        private LocationManager locationManager;
        private final Criteria criteria = new Criteria();
        private String bestAvailableProvider;
        /* Updates are restricted to one every 10 seconds, and only when
         * movement of more than 10 meters has been detected.*/
        private final int minTime = 10000;     // minimum time interval between location updates, in milliseconds
        private final int minDistance = 10;    // minimum distance between location updates, in meters

        private FollowMeLocationSource() {
            // Get reference to Location Manager
            locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);

            // Specify Location Provider criteria
            criteria.setAccuracy(Criteria.ACCURACY_FINE);
            criteria.setPowerRequirement(Criteria.POWER_LOW);
            criteria.setAltitudeRequired(true);
            criteria.setBearingRequired(true);
            criteria.setSpeedRequired(true);
            criteria.setCostAllowed(true);
        }

        private void getBestAvailableProvider() {
            /* The preffered way of specifying the location provider (e.g. GPS, NETWORK) to use 
             * is to ask the Location Manager for the one that best satisfies our criteria.
             * By passing the 'true' boolean we ask for the best available (enabled) provider. */
            bestAvailableProvider = locationManager.getBestProvider(criteria, true);
        }

        /* Activates this provider. This provider will notify the supplied listener
         * periodically, until you call deactivate().
         * This method is automatically invoked by enabling my-location layer. */
        @Override
        public void activate(OnLocationChangedListener listener) {
            // We need to keep a reference to my-location layer's listener so we can push forward
            // location updates to it when we receive them from Location Manager.
            mListener = listener;

            // Request location updates from Location Manager
            if (bestAvailableProvider != null) {
                locationManager.requestLocationUpdates(bestAvailableProvider, minTime, minDistance, this);
            } else {
                // (Display a message/dialog) No Location Providers currently available.
            }
        }

        /* Deactivates this provider.
         * This method is automatically invoked by disabling my-location layer. */
        @Override
        public void deactivate() {
            // Remove location updates from Location Manager
            locationManager.removeUpdates(this);

            mListener = null;
        }

        @Override
        public void onLocationChanged(Location location) {
            /* Push location updates to the registered listener..
             * (this ensures that my-location layer will set the blue dot at the new/received location) */
            if (mListener != null) {
                mListener.onLocationChanged(location);
            }

            /* ..and Animate camera to center on that location !
             * (the reason for we created this custom Location Source !) */
            mMap.animateCamera(CameraUpdateFactory.newLatLng(new LatLng(location.getLatitude(), location.getLongitude())));
        }

        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {

        }

        @Override
        public void onProviderEnabled(String s) {

        }

        @Override
        public void onProviderDisabled(String s) {

        }
    }

}