经纬度范围计算：基于半径的坐标围栏

public static class LatLonUtil
    {
        private static  double PI = 3.14159265;   
        private static double EARTH_RADIUS = 6378137;   
        private static double RAD = Math.PI / 180.0;
   
        //The circumference of the earth is 24,901 miles.   
        //24,901/360 = 69.17 miles / degree     
        /**  
         * @param raidus 单位米  
         * return minLat,minLng,maxLat,maxLng  
         */
        public static double[] getAround(double lat, double lon, int raidus)
        {

            Double latitude = lat;
            Double longitude = lon;

            Double degree = (24901 * 1609) / 360.0;
            double raidusMile = raidus;

            Double dpmLat = 1 / degree;
            Double radiusLat = dpmLat * raidusMile;
            Double minLat = latitude - radiusLat;
            Double maxLat = latitude + radiusLat;

            Double mpdLng = degree * Math.Cos(latitude * (PI / 180));
            Double dpmLng = 1 / mpdLng;
            Double radiusLng = dpmLng * raidusMile;
            Double minLng = longitude - radiusLng;