连续跟踪用户的位置并绘制路径

Question

Well i developed a android program to get your location. Now what i want is to get where you are exactly and track your movements and draw a line on the map of your path. Read a lot of guides but cant make it work at all

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback, LocationListener {

private GoogleMap mMap;
LocationManager locationManager;
String provider;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_maps);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    locationManager = (LocationManager)    getSystemService(Context.LOCATION_SERVICE);
    provider = locationManager.getBestProvider(new Criteria(), false);

}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    Location location= locationManager.getLastKnownLocation(provider);
    double lat =location.getLatitude();
    double lng =location.getLongitude();
    mMap.addMarker(new MarkerOptions().position(new LatLng(lat, lng)).title("Marker"));

    // Add a marker and move the camera

}

@Override
public void onLocationChanged(Location location) {
    Double lat = location.getLatitude();
    Double lng = location.getLongitude();
    mMap.addMarker(new MarkerOptions().position(new LatLng(lat, lng)).title("Marker"));
    mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(lat, lng), 10));
    Log.i("Latitude", lat.toString());

}

Answer 1

Everything you code is write, But you are not working onLocationChanged on starting of Application.

1. getLastKnownLocation returns if location if there's cache otherwise it returns null add a check there.

     if(location!=null) { double lat =location.getLatitude(); double lng =location.getLongitude(); mMap.addMarker(new MarkerOptions().position(new LatLng(lat,lng)).title("Marker")); } 

2. fusedlocation api for better management with location refer here.

3. Try this to addMarker:

    public void drawMarker(double lat,double lon) { if (mMap != null) { MarkerOptions marker = new MarkerOptions().position(new LatLng(lat, lon)).title(" Maps Tutorial").snippet("Android Ruler"); marker.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN)); // Moving Camera to a Location with animation CameraPosition cameraPosition = new CameraPosition.Builder().target(new LatLng(latitude, longitude)).zoom(12).build(); mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition)); mMap.addMarker(marker); } } 

Please refer here: http://coderzpassion.com/android-google-maps-v2-tutorial-with-markers/

4. onLocationChanged(Location location): If the existing location is empty or the current location accuracy is greater than existing accuracy then store the current location.

So, you need to revise onLocationChanged(Location location) and write the application state values you want to change to the code like this:

@Override
public void onLocationChanged(Location location) {

    double latitude = location.getLatitude();
    double longitude = location.getLongitude();

    myLatLng = new LatLng(latitude, longitude);

    zoomToPoints();

    if(!isDirectionDrawn) {

        new LongOperation().execute("");
    }https://developers.google.com/android/reference/com/google/android/gms/location/FusedLocationProviderApi
}

private void moveToCurrentLocation(LatLng currentLocation)
    {
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(currentLocation, 15));
    // Zoom in, animating the camera.
    mMap.animateCamera(CameraUpdateFactory.zoomIn());
    // Zoom out to zoom level 10, animating with a duration of 2 seconds.
    mMap.an


}

Hope it helps.