think\Session::has PHP Method

    public static function has($name, $prefix = null)
    {
        empty(self::$init) && self::boot();
        $prefix = !is_null($prefix) ? $prefix : self::$prefix;
        if (strpos($name, '.')) {
            // 支持数组
            list($name1, $name2) = explode('.', $name);
            return $prefix ? isset($_SESSION[$prefix][$name1][$name2]) : isset($_SESSION[$name1][$name2]);
        } else {
            return $prefix ? isset($_SESSION[$prefix][$name]) : isset($_SESSION[$name]);
        }
    }

 /**
  * 跳转到上次记住的url
  */
 public function restore()
 {
     if (Session::has('redirect_url')) {
         $this->data = Session::get('redirect_url');
         Session::delete('redirect_url');
     }
 }