获取url解析对象

def parse_url(self) -> RequestUrl:
        """
        获取url解析对象
        """
        if self._URL is None:
            current_url = b"%s://%s%s" % (
                encode_str(self.schema),
                encode_str(self.host),
                self._current_url
            )
            self._URL = RequestUrl(current_url)
        return cast(RequestUrl, self._URL)