如何找到在Android应用程序2地理点之间的距离（公路），而不使用谷歌地图API的方向？

问题描述

我开发一个Android应用程序。我需要找到两个地理坐标之间的距离。

I am developing an Android application. I need to find the distance between two geo coordinates.

我用 Location.distanceBetween（）和 Location.distanceTo（）功能。这些功能，得到的直线距离，但实际的距离是不同的，当我们通过公路行进。

I used Location.distanceBetween() and Location.distanceTo() functions. These functions give the straight distance, but the actual distance is different when we travel by road.

推荐答案

使用谷歌API为

public float getDistance(double lat1, double lon1, double lat2, double lon2) {
        String result_in_kms = "";
        String url = "http://maps.google.com/maps/api/directions/xml?origin=" + lat1 + "," + lon1 + "&destination=" + lat2 + "," + lon2 + "&sensor=false&units=metric";
        String tag[] = {"text"};
        HttpResponse response = null;
        try {
            HttpClient httpClient = new DefaultHttpClient();
            HttpContext localContext = new BasicHttpContext();
            HttpPost httpPost = new HttpPost(url);
            response = httpClient.execute(httpPost, localContext);
            InputStream is = response.getEntity().getContent();
            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            Document doc = builder.parse(is);
            if (doc != null) {
                NodeList nl;
                ArrayList args = new ArrayList();
                for (String s : tag) {
                    nl = doc.getElementsByTagName(s);
                    if (nl.getLength() > 0) {
                        Node node = nl.item(nl.getLength() - 1);
                        args.add(node.getTextContent());
                    } else {
                        args.add(" - ");
                    }
                }
                result_in_kms =String.valueOf( args.get(0));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        Float f=Float.valueOf(result_in_kms);
        return f*1000;
    }

或者您可以使用下面的函数

public final static double AVERAGE_RADIUS_OF_EARTH = 6371;
    public float calculateDistance(double userLat, double userLng, double venueLat, double venueLng) {

        double latDistance = Math.toRadians(userLat - venueLat);
        double lngDistance = Math.toRadians(userLng - venueLng);

        double a = (Math.sin(latDistance / 2) * Math.sin(latDistance / 2)) +
                        (Math.cos(Math.toRadians(userLat))) *
                        (Math.cos(Math.toRadians(venueLat))) *
                        (Math.sin(lngDistance / 2)) *
                        (Math.sin(lngDistance / 2));

        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

        return (float) (Math.round(AVERAGE_RADIUS_OF_EARTH * c));

    }

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