/** 
* @desc 根据两点间的经纬度计算距离 
* @param float $lat 纬度值 
* @param float $lng 经度值 
*/function getDistance($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 * $stepTwo;
 return abs(round($calculatedDistance/1000, 2)); 
}