Taobao IP address query class sharing (using Taobao IP library)

<?php

class taobaoIPQuery {

    private $m_ip;
    private $m_content;

    public function __construct($ip) {
        if (isset($ip)) {
            $this->m_ip = $ip;
        } else {
            $this->m_ip = "";
        }
        if (!empty($this->m_ip)) {
            $url_handle = curl_init();
            curl_setopt($url_handle, CURLOPT_URL, "/service/?ip=" . $this->m_ip);
            curl_setopt($url_handle, CURLOPT_RETURNTRANSFER, true);
            $this->m_content = curl_exec($url_handle);
            curl_close($url_handle);
            if ($this->m_content) {
                $this->m_content = json_decode($this->m_content);
                if ($this->m_content->{'code'} == 1) {
                    exit("query error!");
                }
            } else {
                exit("curl error!");
            }
        } else {
            exit("ip address must be not empty!");
        }
    }

    public function get_region() {
        return $this->m_content->{'data'}->{'region'};
    }

    public function get_isp() {
        return $this->m_content->{'data'}->{'isp'};
    }

    public function get_country() {
        return $this->m_content->{'data'}->{'country'};
    }

    public function get_city() {
        return $this->m_content->{'data'}->{'city'};
    }

}