php 根据两地经纬度计算距离，单位可调节。

public function distance($lat1, $lon1, $lat2, $lon2, $unit) {  $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 {        return $miles;      }} public function customerlist(){       $serviceid=$_POST['service_id'];        $lat=$_POST['lat'];        $lng=$_POST['lng'];        // $lat=39.73838; // 纬度        // $lng=116.339128; // 经度        if(empty($lat)||empty($lng)){            Error('定位失败',-2001);        }        // 三元桥 116.464052,39.967359        // 国贸 116.467524,39.914319        // $serviceid=367;       $where['o.serviceid']=$serviceid;       $where['u.type']='1';       // 找到这服务人员下所有的订单      $data =D('Order')->field('o.userid as clientid,sc.scorelevel as starts,u.photo as clientphoto,u.realname as clientname,u.lat,u.lng')->table('t_order as o')->join('t_order_evaluation_s_c as sc on sc.memberid=o.serviceid')->join('t_user as u on o.userid =u.id')->where($where)->group('u.id')->select();      // echo $m->getlastsql();      foreach ($data as $key => &$value) {          if($value['lng']&&$value['lat']){           $data[$key]['distance']=(string)round($this->distance($lat,$lng,$value['lat'],$value['lng'],"K"),2)."Km";           unset($data[$key]['lng']);           unset($data[$key]['lat']);          }else{            unset($data[$key]);          }      }      $count=COUNT($data);            Success(array('list'=>$data,'count'=>$count),1001);    }

如何根据地点知道经纬度。答案是百度拾取器。