android - 使用来自对象类的经纬度在 Google map 上绘制 Pins/MapOverlays

Question

我在下面有这个 MapActivity 类，用于显示 map 并放置用户当前位置的图钉。另一方面，我有一个对象类 VideoLocation，它具有从服务器的 JSON 文件中提取的一些地方的纬度和经度。我还希望在 map 上用图钉绘制位置。

我怎样才能做到这一点？我需要在下面的类(class)中添加什么？

仅供引用，这是我在 ListActivity 上调用对象的纬度和经度的方式:

VideoLocation vidLocation = videoLocations[position];

double lat2 = vidLocation.latitude;
double lng2 = vidLocation.longitude; 

这个类:

public class MyMapActivity extends MapActivity implements OnClickListener {
        public static final String TAG = "GoogleMapsActivity";
        private MapView mapView;
        private LocationManager locationManager;
        Geocoder geocoder;
        Location location;
        LocationListener locationListener;
        CountDownTimer locationtimer;
        MapController mapController;
        MapOverlay mapOverlay = new MapOverlay();

        private VideoLocation[] videoLocations = null;

        @Override
        protected void onCreate(Bundle icicle) {
            super.onCreate(icicle);
            setContentView(R.layout.my_map_activity);
            initComponents();

            JsonDB dbhelper = new JsonDB(MyMapActivity.this);
            SQLiteDatabase db = dbhelper.getWritableDatabase();

            db.beginTransaction();
            videoLocations = dbhelper.getVideoLocations(db);
            db.setTransactionSuccessful();//end transaction
            db.endTransaction();
            db.close();

            final ImageButton refresh = (ImageButton) findViewById(R.id.btn_nav_impressum);
            refresh.setOnClickListener(this);

            final ImageButton search =(ImageButton) findViewById(R.id.btn_nav_locater);
            search.setOnClickListener(this);



            locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
            if (locationManager == null) {
                Toast.makeText(MyMapActivity.this,
                        "Location Manager Not Available", Toast.LENGTH_SHORT)
                        .show();
                return;
            }
            location = locationManager
                    .getLastKnownLocation(LocationManager.GPS_PROVIDER);
            if (location == null)
                location = locationManager
                        .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
            if (location != null) {

                animateMap(location);
                List<Overlay> listOfOverlays = mapView.getOverlays();
                listOfOverlays.clear();
                listOfOverlays.add(mapOverlay);
            }
            locationListener = new LocationListener() {
                @Override
                public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
                }

                @Override
                public void onProviderEnabled(String arg0) {
                }

                @Override
                public void onProviderDisabled(String arg0) {
                }

                @Override
                public void onLocationChanged(Location l) {
                    location = l;
                    locationManager.removeUpdates(this);
                    if (l.getLatitude() == 0 || l.getLongitude() == 0) {
                    } else {
                        double lat = l.getLatitude();
                        double lng = l.getLongitude();
                        showAddress(lat,lng);
                    }
                }
            };
            if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER))
                locationManager.requestLocationUpdates(
                        LocationManager.GPS_PROVIDER, 1000, 10f, locationListener);
            locationManager.requestLocationUpdates(
                    LocationManager.NETWORK_PROVIDER, 1000, 10f, locationListener);
            locationtimer = new CountDownTimer(30000, 5000) {
                @Override
                public void onTick(long millisUntilFinished) {
                    if (location != null)
                        locationtimer.cancel();
                }

                @Override
                public void onFinish() {
                    if (location == null) {
                    }
                }
            };
            locationtimer.start();
        }

        public void animateMap(Location location){
        double lat = location.getLatitude();
            double lng = location.getLongitude();

            GeoPoint point = new GeoPoint((int) (lat * 1E6), (int) (lng * 1E6));
            GeoPoint point2 = new GeoPoint((int) (lat2 * 1E6), (int) (lng2 * 1E6));
            mapController.animateTo(point, new Message());
            mapOverlay.setPointToDraw(point);

        }


        public MapView getMapView() {
            return this.mapView;
        }

        private void initComponents() {
            mapView = (MapView) findViewById(R.id.mapView);
            mapView.setBuiltInZoomControls(true);
            mapController = mapView.getController();
            mapController.setZoom(16);
        }

        @Override
        protected boolean isRouteDisplayed() {
            return false;
        }

        class MapOverlay extends Overlay {
            private GeoPoint pointToDraw;

            public void setPointToDraw(GeoPoint point) {
                pointToDraw = point;
            }

            public GeoPoint getPointToDraw() {
                return pointToDraw;
            }

            @Override
            public boolean draw(Canvas canvas, MapView mapView, boolean shadow,
                    long when) {
                super.draw(canvas, mapView, shadow);

                Point screenPts = new Point();
                mapView.getProjection().toPixels(pointToDraw, screenPts);

                Bitmap bmp = BitmapFactory.decodeResource(getResources(),
                        R.drawable.pin_normal);
                canvas.drawBitmap(bmp, screenPts.x, screenPts.y - 24, null);
                return true;
            }

Answer 1

如果您想在 map 顶部添加图钉(或图像)，添加 ItemizedOverlay 类会更好。
包 com.android.testandroidmap;

import java.util.ArrayList;

import android.app.AlertDialog;
import android.content.Context;
import android.graphics.drawable.Drawable;

import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.OverlayItem;

public class HelloItemizedOverlay extends ItemizedOverlay {

private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();
private Context mContext;

public HelloItemizedOverlay(Drawable defaultMarker, Context context) {
    super(boundCenterBottom(defaultMarker));
    // TODO Auto-generated constructor stub
    mContext = context;
}

@Override
protected OverlayItem createItem(int i) {
    // TODO Auto-generated method stub
    return mOverlays.get(i);
}

@Override
public int size() {
    // TODO Auto-generated method stub
    return mOverlays.size();
}

public void addOverlay(OverlayItem overlay) {
    mOverlays.add(overlay);
    populate();
}

@Override
protected boolean onTap(int index) {
  OverlayItem item = mOverlays.get(index);
  AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
  dialog.setTitle(item.getTitle());
  dialog.setMessage(item.getSnippet());
  dialog.show();
  return true;
}
}

我从 Android Developer Official Guide 得到这个代码，并在您的代码中使用此类，您可以添加叠加层。

添加您需要的所有东西(容器、图钉图像和图钉+坐标叠加层)

List<Overlay> mapOverlays = mapView.getOverlays();
Drawable drawable = this.getResources().getDrawable(R.drawable.androidmarker);
HelloItemizedOverlay itemizedoverlay = new HelloItemizedOverlay(drawable, this);

为了你的图标被之前的类识别，同时实例化坐标，将坐标添加到一个overlayItem + 将overlayItem注册到你之前制作的HelloItemizedOverlay

GeoPoint point = new GeoPoint(19240000,-99120000);
OverlayItem overlayitem = new OverlayItem(point, "Hola, Mundo!", "I'm in Mexico City!");
itemizedoverlay.addOverlay(overlayitem);

最后将叠加层添加到 mapOverlay，它是叠加层的集合。

mapOverlays.add(itemizedoverlay);

这会在我的 map 顶部显示一个图钉，可以根据您想要的任何图像对其进行自定义。如果您还想为每个位置使用不同的图像，只需用您的图像实例化另一个 Drawable 并将该 Drawable 注册到其他 HelloItemizedOverlay。