如何添加BalloonOverLay以显示在Open Street Map（OSM）的mapView上弹出？

Question

我正在使用Open Street View，当用户触摸地图上的特定位置时，我需要弹出窗口。在参考了一些教程后，我发现我必须编写一个名为BalloonOverLay的类。贝娄是我的代码：

公共类AndroidOpenStreetMapViewActivity扩展了Activity {

private MapView myOpenMapView;
private MapController myMapController;

LocationManager locationManager;

ArrayList<OverlayItem> overlayItemArray;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    myOpenMapView = (MapView)findViewById(R.id.openmapview);
    myOpenMapView.setBuiltInZoomControls(true);
    myMapController = myOpenMapView.getController();
    myMapController.setZoom(12);


    //--- Create Overlay
    overlayItemArray = new ArrayList<OverlayItem>();

    DefaultResourceProxyImpl defaultResourceProxyImpl 
        = new DefaultResourceProxyImpl(this);
    MyItemizedIconOverlay myItemizedIconOverlay 
        = new MyItemizedIconOverlay(
                overlayItemArray, null, defaultResourceProxyImpl);
    myOpenMapView.getOverlays().add(myItemizedIconOverlay);
    //---


    locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

    //for demo, getLastKnownLocation from GPS only, not from NETWORK
    Location lastLocation 
        = locationManager.getLastKnownLocation(
                LocationManager.GPS_PROVIDER);
    if(lastLocation != null){
        updateLoc(lastLocation);
    }

    //Add Scale Bar
    ScaleBarOverlay myScaleBarOverlay = new ScaleBarOverlay(this);
    myOpenMapView.getOverlays().add(myScaleBarOverlay);
}

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, myLocationListener);
    locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, myLocationListener);
}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    locationManager.removeUpdates(myLocationListener);
}

private void updateLoc(Location loc){
    GeoPoint locGeoPoint = new GeoPoint(loc.getLatitude(), loc.getLongitude());
    myMapController.setCenter(locGeoPoint);

    setOverlayLoc(loc);

    myOpenMapView.invalidate();
}

private void setOverlayLoc(Location overlayloc){
    GeoPoint overlocGeoPoint = new GeoPoint(overlayloc);
    //---
    overlayItemArray.clear();

    OverlayItem newMyLocationItem = new OverlayItem(
            "My Location", "My Location", overlocGeoPoint);
    overlayItemArray.add(newMyLocationItem);
    //---
}

private LocationListener myLocationListener
= new LocationListener(){

    public void onLocationChanged(Location location) {
        // TODO Auto-generated method stub
        updateLoc(location);
    }

    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }

};

私有类MyItemizedIconOverlay扩展了ItemizedIconOverlay {

    public MyItemizedIconOverlay(
            List<OverlayItem> pList,
            org.osmdroid.views.overlay.ItemizedIconOverlay.OnItemGestureListener<OverlayItem> pOnItemGestureListener,
            ResourceProxy pResourceProxy) {
        super(pList, pOnItemGestureListener, pResourceProxy);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void draw(Canvas canvas, MapView mapview, boolean arg2) {
        // TODO Auto-generated method stub
        super.draw(canvas, mapview, arg2);

        if(!overlayItemArray.isEmpty()){

            //overlayItemArray have only ONE element only, so I hard code to get(0)
            GeoPoint in = overlayItemArray.get(0).getPoint();

            Point out = new Point();
            mapview.getProjection().toPixels(in, out);

            Bitmap bm = BitmapFactory.decodeResource(getResources(), 
                    R.drawable.ic_menu_mylocation);
            canvas.drawBitmap(bm, 
                    out.x - bm.getWidth()/2,    //shift the bitmap center
                    out.y - bm.getHeight()/2,   //shift the bitmap center
                    null);
        }
    }

    @Override
    public boolean onSingleTapUp(MotionEvent event, MapView mapView) {
        // TODO Auto-generated method stub
        //return super.onSingleTapUp(event, mapView);
        return true;
    }
}

我参考了以下教程：

http://android-coding.blogspot.com/2012/06/example-of-implementing-openstreetmap.html#comment-form http://code.google.com/p/osmdroid/ http://android-er.blogspot.in/2012/05/create-multi-marker-openstreetmap-for.html