google-maps - 使用 Google Maps Android API v2 绘制两点之间的路径

Question

Google 更改了 Android map API 并推出了 API V2。以前的绘制路径代码不适用于 API V2。

我已经成功地使用 API V2 绘制了一条路径。我已经搜索了很多解决方案，但没有找到任何答案。所以我分享它的答案。

Answer 1

首先，我们将获得源点和目的地点，我们必须在它们之间绘制路线。然后我们将这些属性传递给下面的函数。

 public String makeURL (double sourcelat, double sourcelog, double destlat, double destlog ){
        StringBuilder urlString = new StringBuilder();
        urlString.append("http://maps.googleapis.com/maps/api/directions/json");
        urlString.append("?origin=");// from
        urlString.append(Double.toString(sourcelat));
        urlString.append(",");
        urlString.append(Double.toString( sourcelog));
        urlString.append("&destination=");// to
        urlString.append(Double.toString( destlat));
        urlString.append(",");
        urlString.append(Double.toString( destlog));
        urlString.append("&sensor=false&mode=driving&alternatives=true");
        urlString.append("&key=YOUR_API_KEY");
        return urlString.toString();
 }

此函数将生成我们将发送以获取 Direction API 响应的 url。然后我们将解析该响应。解析器类是

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";
    // constructor
    public JSONParser() {
    }
    public String getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();           

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }

            json = sb.toString();
            is.close();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }
        return json;

    }
}

这个解析器将返回我们字符串。我们就这样调用它。

JSONParser jParser = new JSONParser();
String json = jParser.getJSONFromUrl(url);

现在我们将这个字符串发送到我们的绘制路径函数。绘制路径函数是

public void drawPath(String  result) {

    try {
            //Tranform the string into a json object
           final JSONObject json = new JSONObject(result);
           JSONArray routeArray = json.getJSONArray("routes");
           JSONObject routes = routeArray.getJSONObject(0);
           JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
           String encodedString = overviewPolylines.getString("points");
           List<LatLng> list = decodePoly(encodedString);
           Polyline line = mMap.addPolyline(new PolylineOptions()
                                    .addAll(list)
                                    .width(12)
                                    .color(Color.parseColor("#05b1fb"))//Google maps blue color
                                    .geodesic(true)
                    );
           /*
           for(int z = 0; z<list.size()-1;z++){
                LatLng src= list.get(z);
                LatLng dest= list.get(z+1);
                Polyline line = mMap.addPolyline(new PolylineOptions()
                .add(new LatLng(src.latitude, src.longitude), new LatLng(dest.latitude,   dest.longitude))
                .width(2)
                .color(Color.BLUE).geodesic(true));
            }
           */
    } 
    catch (JSONException e) {

    }
} 

上面的代码将在mMap上绘制路径。 DecodePoly的代码为

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;
}

由于方向调用可能需要时间，因此我们将在异步任务中完成所有这些操作。我的异步任务是

private class connectAsyncTask extends AsyncTask<Void, Void, String>{
    private ProgressDialog progressDialog;
    String url;
    connectAsyncTask(String urlPass){
        url = urlPass;
    }
    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        progressDialog = new ProgressDialog(MainActivity.this);
        progressDialog.setMessage("Fetching route, Please wait...");
        progressDialog.setIndeterminate(true);
        progressDialog.show();
    }
    @Override
    protected String doInBackground(Void... params) {
        JSONParser jParser = new JSONParser();
        String json = jParser.getJSONFromUrl(url);
        return json;
    }
    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);   
        progressDialog.hide();        
        if(result!=null){
            drawPath(result);
        }
    }
}

希望对您有所帮助。