已知当前地理位置经纬度查询几个点中最近的一个地点demo

1.首先定义一个点与点之间测算距离的方法

2.然后定义找出基本点和集合中最近的一个点的方法

3.取第一条数据即是最近的点的坐标

  public class Location
        {
            public int id { set; get; }//地点的id
            public double lat { set; get; }
            public double lng { set; get; }
            public double distance { set; get; }//地点的距离
        }

  private const double EARTH_RADIUS = 6378.137;//地球半径
        private double rad(double d)
        {
            return d * Math.PI / 180.0;
        }
        //根据两个点的左边测算出距离
        public double GetDistance(Location location1, Location location2)
        {
            double radLat1 = rad(location1.lat);
            double radLat2 = rad(location2.lat);
            double a = radLat1 - radLat2;
            double b = rad(location1.lng) - rad(location2.lng);

            double s = 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)));
            s = s * EARTH_RADIUS;
            s = Math.Round(s * 10000) / 10000;
            return s;
        }
        //找出基本点和数组中最近的一个点
        public List<Location> GetDistance(Location location1, List<Location> location2)
        {
            Location lo=new Location();
            foreach (var item in location2)
            {
                lo.lat=item.lat;
                lo.lng=item.lng;
                item.distance = GetDistance(location1, lo);
            }
            return location2.OrderBy(c=>c.distance).ToList();
        }