从图书借阅状态页面中获取isbn
        :param html:
        :return:

def __get_isbn(self, html):
        """
        从图书借阅状态页面中获取isbn
        :param html:
        :return:
        """

        import re

        reg = re.compile(r'getBookCover\(".*","(.*)"\);')
        res = reg.findall(html)
        if len(res) > 0:
            return res[0]
        else:
            return ''