Android GIS开发系列-- 入门季（10） MapView快速定位到Geometry

我们知道某个Geometry的坐标，但不知道具体的位置，该如何使地图快速定位呢？这时需要用到MapView.setExtent方法，来看下这个方法的介绍：Zooms the map to the given geometry so that geometry fits within the bounds of the map.大体的意思即缩小地图定位到Geometry。上代码：

public class MainActivity extends Activity {

private MapView mapView;
private GraphicsLayer graphicsLayer;
private static final String TILED_WORLD_STREETS_URL = "http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mapView = (MapView) findViewById(R.id.map_view);
mapView.addLayer(new ArcGISTiledMapServiceLayer(TILED_WORLD_STREETS_URL));

findViewById(R.id.location).setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
//快速定位到线
Polyline polyline = new Polyline();
polyline.startPath(new Point(110, 23));
polyline.lineTo(new Point(115, 25));
//由于加载的地图是墨卡托坐标，这里需要转坐标
Polyline polyline2 = (Polyline) GeometryEngine.project(polyline,
SpatialReference.create(SpatialReference.WKID_WGS84),
SpatialReference
.create(SpatialReference.WKID_WGS84_WEB_MERCATOR));
mapView.setExtent(polyline2);
}
});
initLayer();
}

/**
* 添加一条线
*/
private void initLayer() {
graphicsLayer = new GraphicsLayer();
mapView.addLayer(graphicsLayer);
Polyline polyline = new Polyline();
polyline.startPath(new Point(110, 23));
polyline.lineTo(new Point(115, 25));
//由于加载的地图是墨卡托坐标，这里需要转坐标
Polyline polyline2 = (Polyline) GeometryEngine.project(polyline,
SpatialReference.create(SpatialReference.WKID_WGS84),
SpatialReference
.create(SpatialReference.WKID_WGS84_WEB_MERCATOR));
graphicsLayer.addGraphic(new Graphic(polyline2, new SimpleLineSymbol(
Color.RED, 3, SimpleLineSymbol.STYLE.SOLID)));
}

}