在Android片段活动上绘制b/n两个点的路由

implementation 'com.google.android.gms:play-services-maps:17.0.0'

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

<fragment
    android:id="@+id/map_fragment"
    android:name="com.google.android.gms.maps.SupportMapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map_fragment);
    mapFragment.getMapAsync(this);
}

@Override
public void onMapReady(GoogleMap googleMap) {
    // 设置地图属性
    googleMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
    googleMap.getUiSettings().setZoomControlsEnabled(true);

    // 获取路由信息
    LatLng origin = new LatLng(latitude1, longitude1); // 起点坐标
    LatLng destination = new LatLng(latitude2, longitude2); // 终点坐标

    String url = getDirectionsUrl(origin, destination);
    DownloadTask downloadTask = new DownloadTask();
    downloadTask.execute(url);
}

private class DownloadTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... url) {
        String data = "";

        try {
            data = downloadUrl(url[0]);
        } catch (Exception e) {
            Log.d("Background Task", e.toString());
        }

        return data;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        ParserTask parserTask = new ParserTask();
        parserTask.execute(result);
    }
}

private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String, String>>>> {
    @Override
    protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {
        JSONObject jsonObject;
        List<List<HashMap<String, String>>> routes = null;

        try {
            jsonObject = new JSONObject(jsonData[0]);
            DirectionsJSONParser parser = new DirectionsJSONParser();
            routes = parser.parse(jsonObject);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return routes;
    }

    @Override
    protected void onPostExecute(List<List<HashMap<String, String>>> result) {
        ArrayList<LatLng> points = null;
        PolylineOptions polylineOptions = null;

        for (int i = 0; i < result.size(); i++) {
            points = new ArrayList<>();
            polylineOptions = new PolylineOptions();

            List<HashMap<String, String>> path = result.get(i);

            for (int j = 0; j < path.size(); j++) {
                HashMap<String, String> point = path.get(j);

                double lat = Double.parseDouble(point.get("lat"));
                double lng = Double.parseDouble(point.get("lng"));
                LatLng position = new LatLng(lat, lng);

                points.add(position);
            }

            polylineOptions.addAll(points);
            polylineOptions.width(10);
            polylineOptions.color(Color.BLUE);
        }

        if (polylineOptions != null) {
            googleMap.addPolyline(polylineOptions);
        }
    }
}

public class DirectionsJSONParser {
    public List<List<HashMap<String, String>>> parse(JSONObject jsonObject) {
        List<List<HashMap<String, String>>> routes = new ArrayList<>();
        JSONArray jsonArrayRoutes, jsonArrayLegs, jsonArraySteps;

        try {
            jsonArrayRoutes = jsonObject.getJSONArray("routes");

            for (int i = 0; i < jsonArrayRoutes.length(); i++) {
                jsonArrayLegs = ((JSONObject) jsonArrayRoutes.get(i)).getJSONArray("legs");
                List<HashMap<String, String>> path = new ArrayList<>();

                for (int j = 0; j < jsonArrayLegs.length(); j++) {
                    jsonArraySteps = ((JSONObject) jsonArrayLegs.get(j)).getJSONArray("steps");

                    for (int k = 0; k < jsonArraySteps.length(); k++) {
                        String polyline = (String) ((JSONObject) ((JSONObject) jsonArraySteps.get(k)).get("polyline")).get("points");
                        List<LatLng> list = decodePolyline(polyline);

                        for (int l = 0; l < list.size(); l++) {
                            HashMap<String, String> hashMap = new HashMap<>();
                            hashMap.put("lat", Double.toString(list.get(l).latitude));
                            hashMap.put("lng", Double.toString(list.get(l).longitude));
                            path.add(hashMap);
                        }
                    }
                }

                routes.add(path);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return routes;
    }

    private List<LatLng> decodePolyline(String encoded) {
        List<LatLng> poly = new ArrayList<>();
        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 point = new LatLng((double) lat / 1E5, (double) lng / 1E5);
            poly.add(point);
        }

        return poly;
    }
}