android - 在 Google Maps v2 Android 上突出显示指定路线

Question

对，所以我目前在我的应用程序中使用 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 中检索有关路线的许多详细信息，包括沿路线的每条道路的名称、它们对应的起点和终点经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 ，我会得到跟随 JSON 响应（沿路线的一条道路的输出）。

 {
                     "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，我的应用程序解析了这些信息，并在列表视图中简单地列出了道路和方向，如下所示：

我想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任何有用的关于如何在新的 Google Maps API v2 上执行此操作的信息。我看到在 Google Maps v2 上使用折线而不是叠加来绘制线条，但是据我所知，它们只绘制对我没用的直线。是否有使用我掌握的信息（道路名称、起点和终点经纬度坐标、折线点）突出显示路线？任何帮助表示赞赏。

另外，我看到响应中有一个“折线”值，这可能很有用，但我不知道如何解析或使用这些信息。有谁知道我如何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

经过大量的试验和错误，我终于设法让它工作了！它现在在地图上完全突出显示从 A 到 B 的指定路线（如下面的屏幕截图所示）。我还为将来可能需要它的任何人提供了我的代码。

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;
        }
    }

Answer 2

With Android maps api 2 indeed you need to use Polyline class to draw the route on a map (at least it is an easiest way :) ). What you need to do - is to supply list of points along your route.

As for highlighting the active route - there is a handy interface in Polyline class setColor, so you can set whatever color you want to the active route (including an alpha channel)

Polyline line1 = map.addPolyline(new PolylineOptions()
 .add(new LatLng(51.5, -0.1), new LatLng(40.7, -74.0))
 .width(5)
 .color(0xFFFF0000)); //non transparent red

Polyline line2 = map.addPolyline(new PolylineOptions()
 .add(new LatLng(51.5, -0.1), new LatLng(40.8, -74.2))
 .width(5)
 .color(0x7F0000FF)); //semi-transparent blue

Please note you are free to change polyline color anytime you want (f.i. on user click, or something)

As for JSON response from google - route points are encoded, so you can refer to this question to understand how to decode it

Answer 3

有一个简单的解决方案

添加库

编译'com.google.maps.android:android-maps-utils:0.4+'

来自 https://developers.google.com/maps/documentation/android-api/utility/setup的参考

//Getting the points String from response of NavigationAPI call
String polyz=routeSteps.get(0).getOverview_polyline().getPoints();
//Decoding the LatLng Points using PolyUtil Class used from above Library
List<LatLng> points=PolyUtil.decode(polyz);
polyline.addAll(points);
googleMap.addPolyline(polyline);