Java计算两点之间距离 & 三角形面积 & 多边形面积

1. 计算两个直接距离

      /**
        * 单位：米
        *
        * @param lon1
        * @param lat1
        * @param lon2
        * @param lat2
        * @return
        */
       public static double getDistance(double lon1, double lat1, double lon2, double lat2) {
           double radLat1 = rad(lat1);
           double radLat2 = rad(lat2);
           double a = radLat1 - radLat2;
           double b = rad(lon1) - rad(lon2);
           double c = 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)));
           c = c * 6378.137;// 6378.137赤道半径
   
           return (Math.round(c * 10000d) / 10000d) * 1000;
       }
   
       private static double rad(double d) {
           return d * Math.PI / 180.0;
       }

    

2. 三角形面积

       public static Double calculateArea(Loca A, Loca B, Loca