Android 在map上画出路线
具体代码:
- package net.blogjava.mobile.map;
- import java.util.List;
- import Android.app.AlertDialog;
- import android.graphics.Bitmap;
- import android.graphics.BitmapFactory;
- import android.graphics.Canvas;
- import android.graphics.Color;
- import android.graphics.Paint;
- import android.graphics.Path;
- import android.graphics.Point;
- import android.location.Address;
- import android.location.Geocoder;
- import android.os.Bundle;
- import android.view.Menu;
- import com.google.android.maps.GeoPoint;
- import com.google.android.maps.MapActivity;
- import com.google.android.maps.MapController;
- import com.google.android.maps.MapView;
- import com.google.android.maps.Overlay;
- import com.google.android.maps.Projection;
- public class Main extends MapActivity {
- private GeoPoint gpoint1, gpoint2, gpoint3;// 连线的点
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- MapView mapView = (MapView) findViewById(R.id.mapview);
- mapView.setClickable(true);
- mapView.setBuiltInZoomControls(true);
- MapController mapController = mapView.getController();
- mapView.setTraffic(true);// 交通图
- // mapView.setSatellite(true);//卫星图
- // mapView.setStreetView(true);//街景
- MyOverlay myOverlay = new MyOverlay();
- mapView.getOverlays().add(myOverlay);
- mapController.setZoom(15);// 初始放大倍数
- gpoint1 = new GeoPoint((int) (24.477384 * 1000000),
- (int) (118.158216 * 1000000));
- gpoint2 = new GeoPoint((int) (24.488967 * 1000000),
- (int) (118.144277 * 1000000));
- gpoint3 = new GeoPoint((int) (24.491091 * 1000000),
- (int) (118.136781 * 1000000));
- mapController.animateTo(gpoint1);
- }
- @Override
- protected boolean isRouteDisplayed() {
- // TODO Auto-generated method stub
- return false;
- }
- class MyOverlay extends Overlay {
- @Override
- public void draw(Canvas canvas, MapView mapView, boolean shadow) {
- // TODO Auto-generated method stub
- super.draw(canvas, mapView, shadow);
- // 画笔
- Paint paint = new Paint();
- paint.setColor(Color.RED);
- paint.setDither(true);
- paint.setStyle(Paint.Style.STROKE);
- paint.setStrokeJoin(Paint.Join.ROUND);
- paint.setStrokeCap(Paint.Cap.ROUND);
- paint.setStrokeWidth(2);
- Projection projection = mapView.getProjection();
- Point p1 = new Point();
- Point p2 = new Point();
- Point p3 = new Point();
- projection.toPixels(gpoint1, p1);
- projection.toPixels(gpoint2, p2);
- projection.toPixels(gpoint3, p3);
- Path path = new Path();
- path.moveTo(p1.x, p1.y);
- path.lineTo(p2.x, p2.y);
- path.lineTo(p3.x, p3.y);
- canvas.drawPath(path, paint);// 画出路径
- }
- }
- }
main.xml:
- <?xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:Android="http://schemas.android.com/apk/res/android"
- android:orientation="vertical" android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <com.google.android.maps.MapView
- android:id="@+id/mapview" android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:apiKey="0IB7Kn70qp1LT216Hhb-jmHJ8GLTie4p63O77KQ" />
- </LinearLayout>
最后别忘了加权限 :<uses-permission Android:name="android.permission.INTERNET"/>
在<applacation></applacation>之间加<uses-library Android:name="com.google.android.maps" />
Android在google map上画线比较容易实现的,但是现在问题在于如何获取起点和终点之间的路线图。这里我们使用Google Directions API来实现, Google Directions API是一种使用 HTTP 请求计算多个位置间路线的服务。路线可以以文本字符串或纬度/经度坐标的形式指定起点、目的地和路标。Google Directions API 可以使用一系列路标传回多段路线。
Google Directions API 请求是以下形式的 HTTP 网址:http://maps.google.com/maps/api/directions/output?parameters
其中,output 可能是以下任何一个值:
l json(建议)表示以 JavaScript 对象表示法 (JSON) 的形式输出
l xml 表示以 XML 的形式输出
具体参数参见http://code.google.com/intl/zh-CN/apis/maps/documentation/directions/
通过http请求获取线路,接下来我们需要对返回结果进行解析,提取出导航线路的一系列路标。
如果我们只是简单的画图路线路,返回结果中的字段overview_path包含可我们所需要的数据。它包含一个对象,该对象包含一组表示生成路线 的*似(*滑)路径的已编码 points 和 levels。编码算法参见http://code.google.com/intl/zh-CN/apis/maps/documentation /utilities/polylinealgorithm.html说明。
我们只需要提取points字段中的字符串进行解码就可以得到我们所需的一系列点了,将这些点按顺序连接起来就是我们所要的路线图了。
- /**
- * 通过解析google map返回的xml,在map中画路线图
- */
- public void drawRoute(){
- String url = "http://maps.google.com/maps/api/directions/xml?origin=23.055291,113.391802" +
- "&destination=23.046604,113.397510&sensor=false&mode=walking";
- HttpGet get = new HttpGet(url);
- String strResult = "";
- try {
- HttpParams httpParameters = new BasicHttpParams();
- HttpConnectionParams.setConnectionTimeout(httpParameters, 3000);
- HttpClient httpClient = new DefaultHttpClient(httpParameters);
- HttpResponse httpResponse = null;
- httpResponse = httpClient.execute(get);
- if (httpResponse.getStatusLine().getStatusCode() == 200){
- strResult = EntityUtils.toString(httpResponse.getEntity());
- }
- } catch (Exception e) {
- return;
- }
- if (-1 == strResult.indexOf("<status>OK</status>")){
- Toast.makeText(this, "获取导航路线失败!", Toast.LENGTH_SHORT).show();
- this.finish();
- return;
- }
- int pos = strResult.indexOf("<overview_polyline>");
- pos = strResult.indexOf("<points>", pos + 1);
- int pos2 = strResult.indexOf("</points>", pos);
- strResult = strResult.substring(pos + 8, pos2);
- List<GeoPoint> points = decodePoly(strResult);
- MyOverLay mOverlay = new MyOverLay(points);
- List<Overlay> overlays = mMapView.getOverlays();
- overlays.add(mOverlay);
- if (points.size() >= 2){
- mMapController.animateTo(points.get(0));
- }
- mMapView.invalidate();
- }
- /**
- * 解析返回xml中overview_polyline的路线编码
- *
- * @param encoded
- * @return
- */
- private List<GeoPoint> decodePoly(String encoded) {
- List<GeoPoint> poly = new ArrayList<GeoPoint>();
- int index = 0, len = encoded.length();
- int lat = 0, lng = 0;
- while (index < len) {
- int b, shift = 0, result = 0;
- do {
- b = encoded.charAt(index++) - 63;
- result |= (b & 0x1f) << shift;
- shift += 5;
- } while (b >= 0x20);
- int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
- lat += dlat;
- shift = 0;
- result = 0;
- do {
- b = encoded.charAt(index++) - 63;
- result |= (b & 0x1f) << shift;
- shift += 5;
- } while (b >= 0x20);
- int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
- lng += dlng;
- GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6),
- (int) (((double) lng / 1E5) * 1E6));
- poly.add(p);
- }
- return poly;
- }