When we use XPath to crawl web pages, we may encounter such a problem: the list printed using the text method is empty, which?can be caused by non specified direct content.

attention:text() method can only get direct content, string(.) can get whole content and then?composed?in?one?whole?string?returned?to?the?caller.

solution:

<div class="bottom">
        <ul class="unstyled">
          <li><a href="monthdata.php?city=北京">北京</a></li>
          <li><a href="monthdata.php?city=上海">上海</a></li>
          <li><a href="monthdata.php?city=廣州">廣州</a></li>
          <li><a href="monthdata.php?city=深圳">深圳</a></li>
          <li><a href="monthdata.php?city=杭州">杭州</a></li>
          <li><a href="monthdata.php?city=天津">天津</a></li>
          <li><a href="monthdata.php?city=成都">成都</a></li>
          <li><a href="monthdata.php?city=南京">南京</a></li>
          <li><a href="monthdata.php?city=西安">西安</a></li>
          <li><a href="monthdata.php?city=武漢">武漢</a></li>
        </ul>
      </div>

# 第一種方法
li_list = tree.xpath('//div[@class="bottom"]/ul/li/a/text()')

# 第二種方法
li_list = tree.xpath('//div[@class="bottom"]/ul/li//text()')