百度地圖2地之間的距離計算公式

public static double getDistanceFromXtoY(double lat_a, double lng_a,

double lat_b, double lng_b)
{
double pk = (double) (180 / 3.14169);

double a1 = lat_a / pk;
double a2 = lng_a / pk;
double b1 = lat_b / pk;
double b2 = lng_b / pk;

double t1 = Math.cos(a1) * Math.cos(a2) * Math.cos(b1) * Math.cos(b2);
double t2 = Math.cos(a1) * Math.sin(a2) * Math.cos(b1) * Math.sin(b2);
double t3 = Math.sin(a1) * Math.sin(b1);
double tt = Math.acos(t1 + t2 + t3);

return 6366000 * tt;
 }