后端计算两个经纬度点之间的距离，附带通过GeoServer判断点是否在面内

       //地球半径，单位米
        private const double EARTH_RADIUS = 6378137;

        /// <summary>
        /// 计算两点位置的距离，返回两点的距离，单位：米
        /// 该公式为GOOGLE提供，误差小于0.2米
        /// </summary>
        /// <param name="lng1">第一点经度</param>
        /// <param name="lat1">第一点纬度</param>        
        /// <param name="lng2">第二点经度</param>
        /// <param name="lat2">第二点纬度</param>
        /// <returns></returns>
        public static double GetDistance(double lng1, double lat1, double lng2, double lat2)
        {
            double radLat1 = Rad(lat1);
            double radLng1 = Rad(lng1);
            double radLat2 = Rad(lat2);
            double radLng2 = Rad(lng2);
            double a = radLat1 - radLat2;
            double b = radLng1 - radLng2;
            double result = 2 * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / 2), 2) + Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / 2), 2))) * EARTH_RADIUS;
            return result;
            //return Math.Round((result / 1000d), 2);
        }

        /// <summary>
        /// 经纬度转化成弧度
        /// </summary>
        /// <param name="d"></param>
        /// <returns></returns>
        private static double Rad(double d)
        {
            return (double)d * Math.PI / 180d;
        }

 通过GeoServer判断点是否在面内(一定要在GeoServer上发布了面服务)

        /// <summary>
        /// 判断点是否在面内
        /// </summary>
        /// <returns></returns>
        public bool isIn(double JINGDU, double WEIDU)
        {
            bool r = false;
            string url = $"http://XXX.XXX.XX.XX:3939/geoserver/LIANCHENGDIANZIWEILAN/ows?service=WFS&version=1.0.0&request=GetFeature&typeName=LIANCHENGDIANZIWEILAN%3A%E5%8A%9F%E8%83%BD%E5%8C%BA%E5%88%92&maxFeatures=50&outputFormat=application%2Fjson&cql_filter=INTERSECTS(the_geom,POINT( {JINGDU} {WEIDU}))";

            WebClient client = new WebClient();
            try
            {
                client.Encoding = Encoding.UTF8;
                JObject jo = JObject.Parse(client.DownloadString(url));
                var t = jo["totalFeatures"];
                if (t.ToString() != "0")
                {
                    r = true;
                }
                //string result = JObject.Parse(client.DownloadString(url));


            }
            catch (Exception ex)
            {
                //Log4netHelper.Info($"当前时间：{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")} 判断点是否在面内服务失败,TaskID为：");
            }
            return r;
        }

注意：一定要有maxFeatures参数，否则会查询不出来的数据(血的教训)

后面的cql_filter=INTERSECTS就是查询判断