public static function docurl($url, $json, $post = true)
    {
        $ch = curl_init($url);
        curl_setopt($ch, CURLOPT_POST, $post);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_TIMEOUT, 30);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));
        $res = curl_exec($ch);
        curl_close($ch);
        return json_decode($res, true);
    }