谷歌地图计算两个经纬度坐标点的角度

/*
     * 获取两个经纬度坐标点的角度
     * @param LatLng
     * @param LatLng
     */
    // 计算方位角,正北向为0度，以顺时针方向递增
    public static double computeAzimuth(LatLng la1, LatLng la2) {
        double lat1 = la1.latitude, lon1 = la1.longitude, lat2 = la2.latitude,
                lon2 = la2.longitude;
        double result = 0.0;

        int ilat1 = (int) (0.50 + lat1 * 360000.0);
        int ilat2 = (int) (0.50 + lat2 * 360000.0);
        int ilon1 = (int) (0.50 + lon1 * 360000.0);
        int ilon2 = (int) (0.50 + lon2 * 360000.0);

        lat1 = Math.toRadians(lat1);
        lon1 = Math.toRadians(lon1);
        lat2 = Math.toRadians(lat2);
        lon2 = Math.toRadians(lon2);

        if ((ilat1 == ilat2) && (ilon1 == ilon2)) {
            return result;
        } else if (ilon1 == ilon2) {
            if (ilat1 > ilat2)
                result = 180.0;
        } else {
            double c = Math
                    .acos(Math.sin(lat2) * Math.sin(lat1) + Math.cos(lat2)
                            * Math.cos(lat1) * Math.cos((lon2 - lon1)));
            double A = Math.asin(Math.cos(lat2) * Math.sin((lon2 - lon1))
                    / Math.sin(c));
            result = Math.toDegrees(A);
            if ((ilat2 > ilat1) && (ilon2 > ilon1)) {
            } else if ((ilat2 < ilat1) && (ilon2 < ilon1)) {
                result = 180.0 - result;
            } else if ((ilat2 < ilat1) && (ilon2 > ilon1)) {
                result = 180.0 - result;
            } else if ((ilat2 > ilat1) && (ilon2 < ilon1)) {
                result += 360.0;
            }
        }
        return result;
    }