根据经纬度计算距离

//地球平均半径
public static final double EARTH_RADIUS = 6378.137;
//把经纬度转为度
private static double rad(double d ){
return d * Math.PI / 180.0;
}
//开启计算，芭啦芭啦
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 * 10000d) / 10000d;

                 //保留一位小数

DecimalFormat df = new DecimalFormat("0.0");
s = Double.valueOf(df.format(s));
     return s;


}