获得两个GPS坐标之间的距离

private double gps2m(float lat_a, float lng_a, float lat_b, float lng_b) { float pk = (float) (180/3.14169); float a1 = lat_a / pk; float a2 = lng_a / pk; float b1 = lat_b / pk; float b2 = lng_b / pk; float t1 = FloatMath.cos(a1)*FloatMath.cos(a2)*FloatMath.cos(b1)*FloatMath.cos(b2); float t2 = FloatMath.cos(a1)*FloatMath.sin(a2)*FloatMath.cos(b1)*FloatMath.sin(b2); float t3 = FloatMath.sin(a1)*FloatMath.sin(b1); double tt = Math.acos(t1 + t2 + t3); return 6366000*tt; }