根据经纬度计算两点间的距离

/** * 根据两点间的经纬度计算距离
* @param float $lat1 纬度值1
* @param float $lng1 经度值1
* @param float $lat2 纬度值2
* @param float $lng2 经度值2
* @return 距离km
*/
private static function _getDistance($lat1, $lng1, $lat2, $lng2) {
$earthRadius = 6367000;
$lat1 = ($lat1 * pi() ) / 180;
$lng1 = ($lng1 * pi() ) / 180;
$lat2 = ($lat2 * pi() ) / 180;
$lng2 = ($lng2 * pi() ) / 180;
$calcLongitude = $lng2 - $lng1;
$calcLatitude = $lat2 - $lat1;
$stepOne = pow(sin($calcLatitude / 2), 2) + cos($lat1) * cos($lat2) * pow(sin($calcLongitude / 2), 2);
$stepTwo = 2 * asin(min(1, sqrt($stepOne)));
$calculatedDistance = $earthRadius * $stepTwo;
return round($calculatedDistance) / 1000;
}