PHP根据一个给定经纬度的点，进行附近地点查询
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。```php //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);
}
```
