PHP根据一个给定经纬度的点，进行附近地点查询

2015/01/26 37095

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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。
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//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);
}