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 =  * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / ), ) +
              Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / ), )));
             s = s * EARTH_RADIUS;
             s = Math.Round(s * ) / ;
             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();
         }