在Google Maps v2 Android上突出显示指定的路线

Question

是的,所以我目前正在我的应用中使用Google Directions API来检索两个位置之间的路线.

当我发送路线指示请求时,我会在JSON中检索有关路线的一些细节,包括沿路线的每条道路的名称,相应的开始和结束纬度坐标以及它们的折线值.

例如:如果我在两条道路之间发送请求http://maps.googleapis.com/maps/api/directions/json?origin=redfern+ave,+dublin&destination=limetree+ave,+dublin&sensor=false,我会得到遵循JSON响应(沿路线输出一条道路).

 {
                     "distance" : {
                        "text" : "0.2 km",
                        "value" : 203
                     },
                     "duration" : {
                        "text" : "1 min",
                        "value" : 18
                     },
                     "end_location" : {
                        "lat" : 53.435250,
                        "lng" : -6.132140000000001
                     },
                     "html_instructions" : "Head \u003cb\u003eeast\u003c/b\u003e on \u003cb\u003eRedfern Ave.\u003c/b\u003e toward \u003cb\u003eMartello Court\u003c/b\u003e",
                     **"polyline" : {
                        "points" : "woceIvgmd@O}DOkDQqF"**
                     },

到目前为止,我的应用程序解析此信息,并在列表视图中列出道路和方向,如下所示:

我想要做的是在地图上突出显示从A到B的整个路线,但是我在网上找不到有关如何在新的Google Maps API v2上执行此操作的任何有用信息.我看到使用折线而不是叠加来在Google Maps v2上绘制线条,但是据我所知,它们只绘制直线,这对我来说毫无用处.无论如何使用我掌握的信息突出显示路线(道路名称,开始和结束纬度坐标,折线点？任何帮助表示赞赏.

此外,我看到响应中有一个"折线"值可能很有用,但我无法弄清楚如何解析或使用这些信息.有谁知道我如何能够理解这个值来绘制折线？

**"polyline" : {
             "points" : "woceIvgmd@O}DOkDQqF"**

编辑:我的解决方案代码在下面的答案中提供.

Answer 1

经过大量的反复试验,我终于设法让它工作了!它现在完全突出显示地图上从A到B的指定路线(如下面的屏幕截图所示).对于今后可能需要它的人,我也提到了我的代码.

public class PolyMap extends Activity {
        ProgressDialog pDialog;
        GoogleMap map;
        List<LatLng> polyz;
        JSONArray array;
        static final LatLng DUBLIN = new LatLng(53.344103999999990000,
                -6.267493699999932000);

        @SuppressLint("NewApi")
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.map_layout);
            map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            map.moveCamera(CameraUpdateFactory.newLatLngZoom(DUBLIN, 15));
            map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
            new GetDirection().execute();
        }

        class GetDirection extends AsyncTask<String, String, String> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(PolyMap.this);
                pDialog.setMessage("Loading route. Please wait...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(false);
                pDialog.show();
            }

            protected String doInBackground(String... args) {
                Intent i = getIntent();
                String startLocation = i.getStringExtra("startLoc");
                String endLocation = i.getStringExtra("endLoc");
                            startLocation = startLocation.replace(" ", "+");
                    endLocation = endLocation.replace(" ", "+");;
                String stringUrl = "http://maps.googleapis.com/maps/api/directions/json?origin=" + startLocation + ",+dublin&destination=" + endLocation + ",+dublin&sensor=false";
                StringBuilder response = new StringBuilder();
                try {
                    URL url = new URL(stringUrl);
                    HttpURLConnection httpconn = (HttpURLConnection) url
                            .openConnection();
                    if (httpconn.getResponseCode() == HttpURLConnection.HTTP_OK) {
                        BufferedReader input = new BufferedReader(
                                new InputStreamReader(httpconn.getInputStream()),
                                8192);
                        String strLine = null;

                        while ((strLine = input.readLine()) != null) {
                            response.append(strLine);
                        }
                        input.close();
                    }

                    String jsonOutput = response.toString();

                    JSONObject jsonObject = new JSONObject(jsonOutput);

                    // routesArray contains ALL routes
                    JSONArray routesArray = jsonObject.getJSONArray("routes");
                    // Grab the first route
                    JSONObject route = routesArray.getJSONObject(0);

                    JSONObject poly = route.getJSONObject("overview_polyline");
                    String polyline = poly.getString("points");
                    polyz = decodePoly(polyline);

                } catch (Exception e) {

                }

                return null;

            }

            protected void onPostExecute(String file_url) {

                for (int i = 0; i < polyz.size() - 1; i++) {
                    LatLng src = polyz.get(i);
                    LatLng dest = polyz.get(i + 1);
                    Polyline line = map.addPolyline(new PolylineOptions()
                            .add(new LatLng(src.latitude, src.longitude),
                                    new LatLng(dest.latitude,                dest.longitude))
                            .width(2).color(Color.RED).geodesic(true));

                }
                pDialog.dismiss();

            }
        }

        /* Method to decode polyline points */
        private List<LatLng> decodePoly(String encoded) {

            List<LatLng> poly = new ArrayList<LatLng>();
            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;

                LatLng p = new LatLng((((double) lat / 1E5)),
                        (((double) lng / 1E5)));
                poly.add(p);
            }

            return poly;
        }
    }