地图v2绘制多段线并不完全在路上 [英] map v2 drawed polylines are not exactly on the road

问题描述

我从这个网址获取了点数，仅供测试：

  https://maps.googleapis.com/maps/api /directions/json?origin=29.6628166,52.4230969& destination = 27.1908698,56.1678579& key = mykey 
  

我运行这个AsyncTask类来获取和绘制方向，这个类在Map类中用于扩展AppCompatActivity：

  private class方向扩展AsyncTask< String，Void，String> {
 private Context mContext; 
列表< LatLng>奔涛; 
 ProgressDialog对话框; 
 double currentLatitude，currentLongitude，destinationLatitude，destinationLongitude; 
 String walkDistance; 
 
 public direction（Context context，LatLng point）{
 mContext = context; 
 destinationLatitude = point.latitude; 
 destinationLongitude = point.longitude; 
} 
 
 
 @Override 
保护字符串doInBackground（String ... params）{
 JSONObject obj; 
 
 
字符串响应= HttpRequest.get（https://maps.googleapis.com/maps/api/directions/json?origin=29.6628166,52.4230969&existing=27.1908698,56.1678579 &安培;键=的myKey）主体（）; 
 
 
尝试{
 System.out.println（响应内容1是+响应）; 
 
 String jsonOutput = response.toString（）; 
 
 JSONObject jsonObject = new JSONObject（jsonOutput）; 
 
 // routesArray包含所有路由
 JSONArray routesArray = jsonObject.getJSONArray（routes）; 
 //抓住第一条路线
 JSONObject route = routesArray.getJSONObject（0）; 
 
 JSONArray legs = route.getJSONArray（legs）; 
 JSONObject firtsLegs = legs.getJSONObject（0）; 
 
 JSONObject distance = firtsLegs.getJSONObject（distance）; 
 
 
 System.out.println（Response test was：+ distance.getString（text））; 
 
 walkDistance = distance.getString（text）; 
 
 //Toast.makeText（getApplicationContext（），فاصلهشماتانقطه：+ distance.getString（text），Toast.LENGTH_LONG）.show（）; 
 
 
 JSONObject poly = route.getJSONObject（overview_polyline）; 
 String polyline = poly.getString（points）; 
 pontos = decodePoly（polyline）; 
 
 
返回响应; 
 
} catch（Exception e）{
 // TODO自动生成的catch块
 e.printStackTrace（）; 
} 
 return; 
 
 
 $ b @Override 
 protected void onPostExecute（String result）{
 
 Toast.makeText（getApplicationContext（），distance： + walkDistance，Toast.LENGTH_LONG）.show（）; 
 
 /*System.out.println(\"Response content 2 was+ result）; 
 Polygon polygon = mapFragment.addPolygon（new PolygonOptions（）
 .add（new LatLng（35.7513974,51.4350038），
 new LatLng（35.7713974,51.4350038），
 new LatLng（35.7913974 ，51.4350038），
新LatLng（35.7913974,51.5350038））
 .strokeWidth（5）
 .strokeColor（Color.BLUE））; * / 
 
 
 for（int i = 0; i< pontos.size（） -  1; i ++）{
 LatLng src = pontos.get（i）; 
 LatLng dest = pontos.get（i + 1）; 
 try {
 //这里是绘制地图中折线的地方
 / * Polyline line = googleMap.addPolyline（new PolylineOptions（）
 .add（new LatLng（ src.latitude，src.longitude），
 new LatLng（dest.latitude，dest.longitude））
 .width（10）.color（Color.BLUE）.geodesic（false））; 
 
 * / 
 
多边形线= googleMap.addPolygon（新PolygonOptions（）
 .add（新LatLng（src.latitude，src.longitude），
 new LatLng（dest.latitude，dest.longitude））
 .strokeColor（Color.BLUE）.geodesic（true））; 
 
 
 $ b} catch（NullPointerException e）{
 Log.e（Error，NullPointerException onPostExecute：+ e.toString（））; 
} catch（Exception e2）{
 Log.e（Error，Exception onPostExecute：+ e2.toString（））; 
} 
 
} 
 
 dialog.dismiss（）; 
 
 
 @Override 
保护void onPreExecute（）{
 super.onPreExecute（）; 
 dialog = new ProgressDialog（Map.this）; 
 dialog.setMessage（درحالمشخصکردنمسیرشماهستیم，لطفاصبرکنید。）; 
 dialog.setIndeterminate（false）; 
 dialog.setCancelable（false）; 
 dialog.show（）; 
 
 
 / * gps =新GPSTracker（Map.this）; 
 $ b $ //检查GPS是否启用
 if（gps.canGetLocation（））{
 
 currentLatitude = gps.getLatitude（）; 
 currentLongitude = gps.getLongitude（）; 
 
 // \\\
是换行
 Toast.makeText（getApplicationContext（），您的位置是 -  \\\
Lat：+ currentLatitude +\\\
Long：+ currentLongitude ，Toast.LENGTH_LONG）.show（）; 
} else {
 //无法获取位置。 
 // GPS或网络未启用。 
 //要求用户在设置中启用GPS /网络。 
 gps.showSettingsAlert（）; 
} * / 
 
 
 
 
 
} 
 
 @覆盖
保护void onProgressUpdate（ Void ... values）{} 
} 
  

但线路不在路上它看起来像下图：

img src =https://i.stack.imgur.com/eTM2t.jpgalt =在这里输入图片描述>

解决方法

您使用返回的 routes 对象中的 overview_polyline 来绘制路径。正如

i fetched points from this url just for test :

https://maps.googleapis.com/maps/api/directions/json?origin=29.6628166, 52.4230969&destination=27.1908698,56.1678579&key=mykey

i run this AsyncTask class in order to get and draw directions, this class in used in Map class extending AppCompatActivity:

private class direction extends AsyncTask<String, Void, String> {
    private Context mContext;
    List<LatLng> pontos;
    ProgressDialog dialog;
    double currentLatitude, currentLongitude,destinationLatitude,destinationLongitude;
    String walkDistance;

    public direction (Context context,LatLng point){
        mContext = context;
        destinationLatitude = point.latitude;
        destinationLongitude = point.longitude;
    }


    @Override
    protected String doInBackground(String... params) {
        JSONObject obj;


        String response = HttpRequest.get("https://maps.googleapis.com/maps/api/directions/json?origin=29.6628166, 52.4230969&destination=27.1908698,56.1678579&key=mykey").body();


        try {
            System.out.println("Response content 1 was " + response);

            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);

            JSONArray legs = route.getJSONArray("legs");
            JSONObject firtsLegs = legs.getJSONObject(0);

            JSONObject distance = firtsLegs.getJSONObject("distance");


            System.out.println("Response test was : " + distance.getString("text"));

            walkDistance = distance.getString("text");

            //Toast.makeText(getApplicationContext(), "فاصله شما تا نقطه: " + distance.getString("text"), Toast.LENGTH_LONG).show();


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


            return response;

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return "";

    }

    @Override
    protected void onPostExecute(String result) {

        Toast.makeText(getApplicationContext(), "distance : "+walkDistance, Toast.LENGTH_LONG).show();

        /*System.out.println("Response content 2 was " + result);
        Polygon polygon = mapFragment.addPolygon(new PolygonOptions()
        .add(new LatLng(35.7513974, 51.4350038),
             new LatLng(35.7713974, 51.4350038),
             new LatLng(35.7913974, 51.4350038),
             new LatLng(35.7913974, 51.5350038))
        .strokeWidth(5)
        .strokeColor(Color.BLUE));*/


        for (int i = 0; i < pontos.size() - 1; i++) {
            LatLng src = pontos.get(i);
            LatLng dest = pontos.get(i + 1);
            try{
                //here is where it will draw the polyline in your map
                /*Polyline line = googleMap.addPolyline(new PolylineOptions()
                        .add(new LatLng(src.latitude, src.longitude),
                                new LatLng(dest.latitude,                dest.longitude))
                        .width(10).color(Color.BLUE).geodesic(false));

                */

                Polygon line = googleMap.addPolygon(new PolygonOptions()
                        .add(new LatLng(src.latitude, src.longitude),
                                new LatLng(dest.latitude,                dest.longitude))
                        .strokeColor(Color.BLUE).geodesic(true));



            }catch(NullPointerException e){
                Log.e("Error", "NullPointerException onPostExecute: " + e.toString());
            }catch (Exception e2) {
                Log.e("Error", "Exception onPostExecute: " + e2.toString());
            }

        }

        dialog.dismiss();
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        dialog = new ProgressDialog(Map.this);
        dialog.setMessage("در حال مشخص کردن مسیر شما هستیم، لطفا صبر کنید.");
        dialog.setIndeterminate(false);
        dialog.setCancelable(false);
        dialog.show();


        /*gps = new GPSTracker(Map.this);

        // Check if GPS enabled
        if(gps.canGetLocation()) {

            currentLatitude = gps.getLatitude();
            currentLongitude = gps.getLongitude();

            // \n is for new line
            Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + currentLatitude + "\nLong: " + currentLongitude, Toast.LENGTH_LONG).show();
        } else {
            // Can't get location.
            // GPS or network is not enabled.
            // Ask user to enable GPS/network in settings.
            gps.showSettingsAlert();
        }*/





    }

    @Override
    protected void onProgressUpdate(Void... values) {}
}

but lines are not on the road and it looks like bellow image :

解决方案

You are using the overview_polyline from the returned routes object to draw your path. As the documentation says (emphasis mine)

overview_polyline contains a single points object that holds an encoded polyline representation of the route. This polyline is an approximate (smoothed) path of the resulting directions.

You will get a much better approximation if you draw the polyline object of each step that you receive in the legs array.

From your example (the red line represents the overview_polyline and the blue line represents the polyline object of the first step received):

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