百度地图覆盖物的描述

 
package com.njupt.bmap_helloworld;  
  
import com.baidu.mapapi.BMapManager;  
import com.baidu.mapapi.GeoPoint;  
import com.baidu.mapapi.MKGeneralListener;  
import com.baidu.mapapi.MapActivity;  
import com.baidu.mapapi.MapController;  
import com.baidu.mapapi.MapView;  
import com.baidu.mapapi.Overlay;  
  
import android.os.Bundle;  
import android.app.Activity;  
import android.graphics.Canvas;  
import android.graphics.Paint;  
import android.graphics.Point;  
import android.view.Menu;  
import android.widget.Toast;  
  
public class MainActivity extends MapActivity {  
  
    private MapView mapView;//百度地图的相关控件  
    private BMapManager bMapManager;//加载地图的引擎  
    private String keyString = "04763B1D8C925195965E838C6E59DB767DAE4BA7";//百度地图的key  
    private MapController mapController;//在百度地图上添加一些控件,比如放大或缩小控件  
      
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
          
        mapView = (MapView) findViewById(R.id.bmapView);  
        bMapManager = new BMapManager(MainActivity.this);  
          
        //必须要加载key  
        bMapManager.init(keyString, new MKGeneralListener() {  
              
            @Override  
            public void onGetPermissionState(int arg0) {  
                if(arg0 == 300){  
                    Toast.makeText(MainActivity.this, "输入的key有误,请核实...", 1).show();  
                }  
            }  
              
            @Override  
            public void onGetNetworkState(int arg0) {  
                // TODO Auto-generated method stub  
                  
            }  
        });  
          
        initMapActivity(bMapManager);  
        mapView.setBuiltInZoomControls(true);//表示可以设置缩放功能  
        mapController = mapView.getController();  
        mapController.setZoom(12);  
        mapView.getOverlays().add(new MyOverLay());  
          
//      mapView.setTraffic(true);显示交通地图  
//      mapView.setSatellite(true);显示卫星地图  
    }  
  
    public class MyOverLay extends Overlay{  
        //构建地图上的一个点  
        private GeoPoint geoPoint = new GeoPoint((int)(39.915*1E6), (int)(116.404*1E6));  
        //声明一个画笔工具  
        private Paint paint = new Paint();  
          
        @Override  
        public void draw(Canvas arg0, MapView arg1, boolean arg2) {  
            super.draw(arg0, arg1, arg2);  
              
            Point point = mapView.getProjection().toPixels(geoPoint, null);  
            arg0.drawText("*这里是天安门", point.x, point.y, paint);  
        }  
    }  
    @Override  
    protected void onDestroy() {  
        super.onDestroy();  
          
        if(bMapManager != null){  
            bMapManager.destroy();  
            bMapManager = null;  
        }  
    }  
      
    @Override  
    protected void onResume() {  
        super.onResume();  
          
        if(bMapManager != null){  
            bMapManager.start();  
        }  
    }  
      
    @Override  
    protected void onPause() {  
        super.onPause();  
          
        if(bMapManager != null){  
            bMapManager.stop();  
        }  
    }  
    @Override  
    protected boolean isRouteDisplayed() {  
        // TODO Auto-generated method stub  
        return false;  
    }  
    @Override  
    public boolean onCreateOptionsMenu(Menu menu) {  
        // Inflate the menu; this adds items to the action bar if it is present.  
        getMenuInflater().inflate(R.menu.main, menu);  
        return true;  
    }  
  
}