PHP計算地圖上兩點間的距離

 
<?php
class GeoHelper
{
    /**


 * @param int $lat1
 * @param int $lon1
 * @param int $lat2
 * @param int $lon2
 * @param string $unit
 * @return
 */
public static function distance($lat1, $lon1, $lat2, $lon2, $unit = "K")
{
    $theta = $lon1 - $lon2;
    $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad
        ($lat2)) * cos(deg2rad($theta));
    $dist = acos($dist);
    $dist = rad2deg($dist);
    $miles = $dist * 60 * 1.1515;
    $unit = strtoupper($unit);

    if ($unit == "K") {
        return ($miles * 1.609344);
    } else
        if ($unit == "N") {
            return ($miles * 0.8684);
        } else { //mi
            return $miles;
        }
}

/**
 * 
 * @param string $address
 * @param string $apikey
 * @return array [1]:lat [0]:lng
 */
public static function getLatLng($address, $apikey)
{
    $find = array("\\n", "\\r", " ");
    $replace = array("", "", "+");
    $address = str_replace($find, $replace, $address);
    $url = 'http://maps.google.com/maps/geo?q=' . $address . '&key=' . $apikey .
        '&sensor=false&output=xml&oe=utf8';
    $response = self::xml2array($url);
    $coordinates = $response['kml']['Response']['Placemark']['Point']['coordinates'];
    if (!empty($coordinates)) {
        $point_array = split(",", $coordinates);
        return $point_array;
    }
}

}
</pre>