java 已知两个地点经纬度算距离（非常精确）

java 已知两个地点经纬度算距离（非常精确）

package com.lbnet.lzx.util;

public class GoogleMap {


private static final double EARTH_RADIUS = 6378.137;
private static double rad(double d)
{
return d * Math.PI / 180.0;
}
/**
* ????}?????????????/γ???
* @param lat1
* @param lng1
* @param lat2
* @param lng2
* @return
*/
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 * 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;
}
public static double D_jw(double wd1,double jd1,double wd2,double jd2)
{
double x,y,out;
double PI=3.14159265;
double R=6.371229*1e6;

x=(jd2-jd1)*PI*R*Math.cos( ((wd1+wd2)/2) *PI/180)/180;
y=(wd2-wd1)*PI*R/180;
out=Math.hypot(x,y);
return out/1000;
}

public static void main(String args[]){
//31.1795100,121.3944810
System.out.println(GoogleMap.D_jw(31.192609,121.431577,31.1822952,121.4314814));
}
}