book_admin/application/common/service/DomainService.php

<?php
/**
 * Created by PhpStorm.
 * User: Elton
 * Date: 2019/3/29
 * Time: 14:34
 */

namespace app\common\service;


class DomainService extends BaseService
{
    public static function instance()
    {
        if(self::$self == NULL){
            self::$self = new self();
        }

        return self::$self;
    }


}