实现原理先算出该点周围的矩形的四个点，然后使用经纬度去直接匹配数据库中的记录。

   //获取周围坐标
   public function returnSquarePoint($lng, $lat,$distance = 0.5){
         $earthRadius = 6378138;
        $dlng =  2 * asin(sin($distance / (2 * $earthRadius)) / cos(deg2rad($lat)));
        $dlng = rad2deg($dlng);
        $dlat = $distance/$earthRadius;
        $dlat = rad2deg($dlat);
        return array(
                       'left-top'=>array('lat'=>$lat + $dlat,'lng'=>$lng-$dlng),
                       'right-top'=>array('lat'=>$lat + $dlat, 'lng'=>$lng + $dlng),
                       'left-bottom'=>array('lat'=>$lat - $dlat, 'lng'=>$lng - $dlng),
                       'right-bottom'=>array('lat'=>$lat - $dlat, 'lng'=>$lng + $dlng)
        );
   }
   //计算两个坐标的直线距离
    
   public function getDistance($lat1, $lng1, $lat2, $lng2){      
          $earthRadius = 6378138; //近似地球半径米
          // 转换为弧度
          $lat1 = ($lat1 * pi()) / 180;
          $lng1 = ($lng1 * pi()) / 180;
          $lat2 = ($lat2 * pi()) / 180;
          $lng2 = ($lng2 * pi()) / 180;
          // 使用半正矢公式  用尺规来计算
        $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);
   }