如何使用Google Maps API v2获取两个gepoints之间的距离？

时间：2013-08-30 10:02:15

标签： android google-maps distance

我正在尝试使用Google Maps API v2计算两个GeoPoints之间的距离。

地图绘制正确的线但是当我试图获得距离时，我得到0.5公里而不是70公里。

enter image description here

本课程获取有关道路的信息。

public class GMapV2Direction {

public final static String MODE_DRIVING = "driving";
public final static String MODE_WALKING = "walking";

public GMapV2Direction() { }

public Document getDocument(LatLng start, LatLng end, String mode) {
    String url = "http://maps.googleapis.com/maps/api/directions/xml?"
            + "origin=" + start.latitude + "," + start.longitude
            + "&destination=" + end.latitude + "," + end.longitude
            + "&sensor=false&units=metric&mode=driving";

    try {
        HttpClient httpClient = new DefaultHttpClient();
        HttpContext localContext = new BasicHttpContext();
        HttpPost httpPost = new HttpPost(url);
        HttpResponse response = httpClient.execute(httpPost, localContext);
        InputStream in = response.getEntity().getContent();
        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document doc = builder.parse(in);
        return doc;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

public String getDurationText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("duration");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DurationText", node2.getTextContent());
    return node2.getTextContent();
}

public int getDurationValue (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("duration");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "value"));
    Log.i("DurationValue", node2.getTextContent());
    return Integer.parseInt(node2.getTextContent());
}

public String getDistanceText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DistanceText", node2.getTextContent());
    return node2.getTextContent();
}

public int getDistanceValue (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    Node node1 = nl1.item(0);
    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "value"));
    Log.i("DistanceValue", node2.getTextContent());
    return Integer.parseInt(node2.getTextContent());
}

public String getStartAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("start_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getEndAddress (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("end_address");
    Node node1 = nl1.item(0);
    Log.i("StartAddress", node1.getTextContent());
    return node1.getTextContent();
}

public String getCopyRights (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("copyrights");
    Node node1 = nl1.item(0);
    Log.i("CopyRights", node1.getTextContent());
    return node1.getTextContent();
}

public ArrayList<LatLng> getDirection (Document doc) {
    NodeList nl1, nl2, nl3;
    ArrayList<LatLng> listGeopoints = new ArrayList<LatLng>();
    nl1 = doc.getElementsByTagName("step");
    if (nl1.getLength() > 0) {
        for (int i = 0; i < nl1.getLength(); i++) {
            Node node1 = nl1.item(i);
            nl2 = node1.getChildNodes();

            Node locationNode = nl2.item(getNodeIndex(nl2, "start_location"));
            nl3 = locationNode.getChildNodes();
            Node latNode = nl3.item(getNodeIndex(nl3, "lat"));
            double lat = Double.parseDouble(latNode.getTextContent());
            Node lngNode = nl3.item(getNodeIndex(nl3, "lng"));
            double lng = Double.parseDouble(lngNode.getTextContent());
            listGeopoints.add(new LatLng(lat, lng));

            locationNode = nl2.item(getNodeIndex(nl2, "polyline"));
            nl3 = locationNode.getChildNodes();
            latNode = nl3.item(getNodeIndex(nl3, "points"));
            ArrayList<LatLng> arr = decodePoly(latNode.getTextContent());
            for(int j = 0 ; j < arr.size() ; j++) {
                listGeopoints.add(new LatLng(arr.get(j).latitude, arr.get(j).longitude));
            }

            locationNode = nl2.item(getNodeIndex(nl2, "end_location"));
            nl3 = locationNode.getChildNodes();
            latNode = nl3.item(getNodeIndex(nl3, "lat"));
            lat = Double.parseDouble(latNode.getTextContent());
            lngNode = nl3.item(getNodeIndex(nl3, "lng"));
            lng = Double.parseDouble(lngNode.getTextContent());
            listGeopoints.add(new LatLng(lat, lng));
        }
    }

    return listGeopoints;
}

private int getNodeIndex(NodeList nl, String nodename) {
    for(int i = 0 ; i < nl.getLength() ; i++) {
        if(nl.item(i).getNodeName().equals(nodename))
            return i;
    }
    return -1;
}

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

这门课得到路线。

 public class test_GoogleMaps extends FragmentActivity {

String distance1;
double DoubleDistance = 0;
String distance;


Document document;
GMapV2Direction v2GetRouteDirection;
LatLng fromPosition;
LatLng toPosition;
GoogleMap mGoogleMap;
MarkerOptions markerOptions;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.test_googlemaps);
    v2GetRouteDirection = new GMapV2Direction();
    SupportMapFragment supportMapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mGoogleMap = supportMapFragment.getMap();

    // Enabling MyLocation in Google Map

    mGoogleMap.getUiSettings().setZoomControlsEnabled(true);
    mGoogleMap.getUiSettings().setCompassEnabled(true);
    mGoogleMap.getUiSettings().setMyLocationButtonEnabled(true);
    mGoogleMap.getUiSettings().setAllGesturesEnabled(true);
    mGoogleMap.setTrafficEnabled(true);
    mGoogleMap.animateCamera(CameraUpdateFactory.zoomTo(12));
    markerOptions = new MarkerOptions();
    fromPosition = new LatLng(43.21275, 27.88652);
    toPosition = new LatLng(43.49394, 27.41224);
    GetRouteTask getRoute = new GetRouteTask();
    getRoute.execute();



}



 // This class Get Route on the map

private class GetRouteTask extends AsyncTask<String, Void, String> {


    private ProgressDialog Dialog;
    String response = "";
    @Override
    protected void onPreExecute() {
        Dialog = new ProgressDialog(test_GoogleMaps.this);
        Dialog.setMessage("Loading route...");
        Dialog.show();
    }

    @Override
    protected String doInBackground(String... urls) {
        //Get All Route values
        document = v2GetRouteDirection.getDocument(fromPosition, toPosition, GMapV2Direction.MODE_DRIVING);

        //get distance and convert it in double
        distance = v2GetRouteDirection.getDistanceText(document).toString();
        distance1 = distance.substring(0,3);

        DoubleDistance = Double.parseDouble(distance1);



        response = "Success";
        return response;

    }

    @Override
    protected void onPostExecute(String result) {


        mGoogleMap.clear();
        if(response.equalsIgnoreCase("Success")){


            ArrayList<LatLng> directionPoint = v2GetRouteDirection.getDirection(document);
            PolylineOptions rectLine = new PolylineOptions().width(10).color(
                    Color.RED);

            for (int i = 0; i < directionPoint.size(); i++) {
                rectLine.add(directionPoint.get(i));
            }
            // Adding route on the map
            mGoogleMap.addPolyline(rectLine);
            markerOptions.position(toPosition);
            markerOptions.draggable(true);
            mGoogleMap.addMarker(markerOptions);



        }



        Dialog.dismiss();
        TextView dist = (TextView) findViewById(R.id.distance);

        dist.setText(String.format("Traveled km.\n %f",DoubleDistance));
    }
}
@Override
protected void onStop() {
    super.onStop();
    finish();
}  }

解决方案：

我刚从XML获取最后一项。

 //get distance in km

public String getDistanceText (Document doc) {
    NodeList nl1 = doc.getElementsByTagName("distance");
    int i;

   //get the last tag from XML

   for(i = 0;i<nl1.getLength();i++){

    }

    if(i==i){
        i--;
    }

    Node node1 = nl1.item(i);


    NodeList nl2 = node1.getChildNodes();
    Node node2 = nl2.item(getNodeIndex(nl2, "text"));
    Log.i("DistanceText", node2.getTextContent());
    return node2.getTextContent();
}

2 个答案:

答案 0 :(得分：1)

您正在解析step值的距离数据。您应该再次查看xml。它显示正确的data

见这个

enter image description here

答案 1 :(得分：0)

尝试在 getDirection

上对所有距离和持续时间求和 
            locationNode = nl2.item(getNodeIndex(nl2, "distance"));
            nl3 = locationNode.getChildNodes();
            Node valNode = nl3.item(getNodeIndex(nl3, "value"));
            // SUM DISTANCE STEP
            TOTAL_DISTANCE += Integer.parseInt(valNode.getTextContent());  

            locationNode = nl2.item(getNodeIndex(nl2, "duration"));
            nl3 = locationNode.getChildNodes();
            valNode = nl3.item(getNodeIndex(nl3, "value"));
            // SUM DURATION STEP
            TOTAL_DURATION += Integer.parseInt(valNode.getTextContent());
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