java 计算两个经纬度之间距离

public class Distance
{

private static final double EARTH_RADIUS = 6378137;
private static double rad(double d)
{
return d * Math.PI / 180.0;
}

/**
* 根据两点间经纬度坐标（double值），计算两点间距离，单位为米
* @param lng1
* @param lat1
* @param lng2
* @param lat2
* @return 返回单位m
*/
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;
}

/**
* @param args
*/
public static void main(String[] args)
{
// TODO 自动生成方法存根
double distance = GetDistance(121.491909,31.233234,121.411994,31.206134);
System.out.println("Distance is:"+distance);
}

}