百度地图中的多地图覆盖物的实现(一)

 package com.njupt.bmap_helloworld;  
  
import java.util.ArrayList;  
import java.util.List;  
  
import com.baidu.mapapi.BMapManager;  
import com.baidu.mapapi.GeoPoint;  
import com.baidu.mapapi.ItemizedOverlay;  
import com.baidu.mapapi.MKGeneralListener;  
import com.baidu.mapapi.MapActivity;  
import com.baidu.mapapi.MapController;  
import com.baidu.mapapi.MapView;  
import com.baidu.mapapi.OverlayItem;  
  
import android.os.Bundle;  
import android.app.Activity;  
import android.graphics.drawable.Drawable;  
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);//设置缩放级别  
          
//      mapView.setTraffic(true);显示交通地图  
//      mapView.setSatellite(true);显示卫星地图  
          
        Drawable drawable = getResources().getDrawable(R.drawable.iconmarka);  
        mapView.getOverlays().add(new MyOverLayItem(drawable));  
    }  
  
    public class MyOverLayItem extends ItemizedOverlay





{  
  
        private List list = new ArrayList();  
        //定义一组坐标,每一个都是double类型  
        private double mLat1 = 39.90923;//纬度  
        private double mLon1 = 116.397428;//经度  
          
        private double mLat2 = 39.9022;  
        private double mLon2 = 116.3922;  
          
        private double mLat3 = 39.917723;  
        private double mLon3 = 116.37222;  
          
        //用于在地图上标志坐标,用一个图片标志  
        public MyOverLayItem(Drawable drawable) {  
            super(drawable);  
            //第一组数据在地图上的标注点  
            GeoPoint geoPoint1 = new GeoPoint((int)(mLat1*1E6), (int)(mLon1*1E6));  
            GeoPoint geoPoint2 = new GeoPoint((int)(mLat2*1E6), (int)(mLon2*1E6));  
            GeoPoint geoPoint3 = new GeoPoint((int)(mLat3*1E6), (int)(mLon3*1E6));  
              
            list.add(new OverlayItem(geoPoint1, "Point1", "Point1"));  
            list.add(new OverlayItem(geoPoint2, "Point2", "Point2"));  
            list.add(new OverlayItem(geoPoint3, "Point3", "Point3"));  
              
            populate();//刷新地图,不加的话会报NullPointException  
        }  
          
        //返回list集合中的每一个坐标  
        @Override  
        protected OverlayItem createItem(int arg0) {  
            return list.get(arg0);  
        }  
  
        @Override  
        public int size() {  
            return list.size();  
        }  
          
        @Override  
        protected boolean onTap(int i) {//设置点击事件  
            Toast.makeText(MainActivity.this, list.get(i).getSnippet(), 1).show();  
            return true;  
        }  
    }  
    @Override  
    protected void onDestroy() {  
        super.onDestroy();  
          
        if(bMapManager != null){  
            bMapManager.destroy();  
            bMapManager = null;  
        }  
    }  
      
    @Override  
    protected void onResume() {  
        super.o