如何在python中获取div tag中存在的标记？

Question

我正在用python抓取一个网站http://i.cantonfair.org.cn/en/expexhibitorlist.aspx?categoryno=411。 我想在一个div标记中得到一个链接，其中有两个a标记，如：

<div id="main_category">
  <div class="tit1"><a href="#" onclick="ExpandStage(1);"><strong>Phase 1</strong><br />April 15 - 19</a></div>
  <ul id="phase1">   
    <li><a href="expexhibitorlist.aspx?categoryno=411">Consumer Electronics and Information Products</a></li>
    <li><a href="expexhibitorlist.aspx?categoryno=412">Electronic and Electrical Products</a></li>

我只想要像这样的标签

<a href="expexhibitorlist.aspx?categoryno=411">Consumer Electronics and Information Products</a>

。另外，如何使用regex查找这些URL？你知道吗

我正在这样努力

from bs4 import BeautifulSoup
import re
import urllib.request
r = urllib.request.urlopen('http://i.cantonfair.org.cn/en/expexhibitorlist.aspx?categoryno=410').read()
soup = BeautifulSoup(r, "html.parser")
letters = soup.find_all("div",{"id":"main_category"})
for element in letters:
categories = element.a.get_text()
print (categories)

Answer 1

我使用的是Python2.7，下面的代码对我很有用。python3可以使用相同的方法。希望能有帮助：

from bs4 import BeautifulSoup as bs
from urllib2 import urlopen
r = urlopen('http://i.cantonfair.org.cn/en/expexhibitorlist.aspx?categoryno=410').read()
soup = bs(r, "lxml")
lis = soup.find_all("li")
hrefs = [c.a['href'] for c in lis]
print hrefs