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20人在不同的方向位置，推荐一个中心位置！！！

``````  /**
* Calculation of the geographic midpoint (also known as the geographic center,
* or center of gravity) for two or more points on the earth's surface Ref:
* http://www.geomidpoint.com/calculation.html
*
* @param points
* @return
*/
public static Point2D.Double midpoint(List<Point2D.Double> points) {
double Totweight = 0;
double xt = 0;
double yt = 0;
double zt = 0;
for (Point2D.Double point : points) {
Double latitude = point.x;
Double longitude = point.y;

/**
* Convert Lat and Lon from degrees to radians.
*/
double latn = latitude * Math.PI / 180;
double lonn = longitude * Math.PI / 180;

/**
* Convert lat/lon to Cartesian coordinates
*/
double xn = Math.cos(latn) * Math.cos(lonn);
double yn = Math.cos(latn) * Math.sin(lonn);
double zn = Math.sin(latn);

/**
* Compute weight (by time) If locations are to be weighted equally,
* set wn to 1
*/
double years = 0;
double months = 0;
double days = 0;
double wn = true ? 1 : (years * 365.25) + (months * 30.4375) + days;

/**
* Compute combined total weight for all locations.
*/
Totweight = Totweight + wn;
xt += xn * wn;
yt += yn * wn;
zt += zn * wn;
}

/**
* Compute weighted average x, y and z coordinates.
*/
double x = xt / Totweight;
double y = yt / Totweight;
double z = zt / Totweight;

/**
* If abs(x) < 10-9 and abs(y) < 10-9 and abs(z) < 10-9 then the
* geographic midpoint is the center of the earth.
*/
double lat = -0.001944;
double lon = -78.455833;
if (Math.abs(x) < Math.pow(10, -9) && Math.abs(y) < Math.pow(10, -9) && Math.abs(z) < Math.pow(10, -9)) {
} else {

/**
* Convert average x, y, z coordinate to latitude and longitude.
* Note that in Excel and possibly some other applications, the
* parameters need to be reversed in the atan2 function, for
* example, use atan2(X,Y) instead of atan2(Y,X).
*/
lon = Math.atan2(y, x);
double hyp = Math.sqrt(x * x + y * y);
lat = Math.atan2(z, hyp);

/**
* Convert lat and lon to degrees.
*/
lat = lat * 180 / Math.PI;
lon = lon * 180 / Math.PI;
}
return new Point2D.Double(lat, lon);
}
``````