计算两个坐标之间的距离

public static double getDistance(double lat1, double lng1, double lat2, double lng2) {
double radLat1 = rad(lat1);
double radLat2 = rad(lat2);
double a = radLat1 - radLat2;
double b = rad(lng1) - rad(lng2);
double s = 2.0D * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2.0D), 2.0D)
+ Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2.0D), 2.0D)));
s *= EARTH_RADIUS;
s = Math.round(s * 10000.0D) / 10000.0D;
s *= 1000.0D;
return s;
}