计算两个经纬度坐标的直线距离

private static final double EARTH_RADIUS = 6378137;

private static double rad(double d) {
return d * Math.PI / 180.0;
}

public static double getDistance(double lng1, double lat1, double lng2,
double lat2) {
double radLat1 = rad(lat1);
double radLat2 = rad(lat2);
double a = radLat1 - radLat2;
double b = rad(lng1) - rad(lng2);
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;
}