原文出处：
http://www.cnblogs.com/LBSer/p/3733550.html
/**
*
* @param lat1 The y coordinate of the first point, in radians
* @param lon1 The x coordinate of the first point, in radians
* @param lat2 The y coordinate of the second point, in radians
* @param lon2 The x coordinate of the second point, in radians
* @return The distance between the two points, as determined by the Haversine formula, in radians.
*/
public
static
double
distHaversineRAD(
double
lat1,
double
lon1,
double
lat2,
double
lon2) {
if
(lat1 == lat2 && lon1 == lon2)
return
0.0
;
double
hsinX = Math.sin((lon1 - lon2) *
0.5
);
double
hsinY = Math.sin((lat1 - lat2) *
0.5
);
double
h = hsinY * hsinY +
(Math.cos(lat1) * Math.cos(lat2) * hsinX * hsinX);
return
2
* Math.atan2(Math.sqrt(h), Math.sqrt(
1
- h));
}