Python verwendet vier Methoden, um eine vergleichende Analyse aller Links auf der aktuellen Seite zu erreichen

'''
得到当前页面所有连接
'''
import requests
import re
from bs4 import BeautifulSoup
from lxml import etree
from selenium import webdriver
url = 'http://www.testweb.com'
r = requests.get(url)
r.encoding = 'gb2312'
# 利用 re （太黄太暴力！）
matchs = re.findall(r"(?<=href=\").+?(?=\")|(?<=href=\&#39;).+?(?=\&#39;)" , r.text)
for link in matchs:
  print(link)
print()
# 利用 BeautifulSoup4 （DOM树）
soup = BeautifulSoup(r.text,&#39;lxml&#39;)
for a in soup.find_all(&#39;a&#39;):
  link = a[&#39;href&#39;]
  print(link)
print()
# 利用 lxml.etree （XPath）
tree = etree.HTML(r.text)
for link in tree.xpath("//@href"):
  print(link)
print()
# 利用selenium（要开浏览器！）
driver = webdriver.Firefox()
driver.get(url)
for link in driver.find_elements_by_tag_name("a"):
  print(link.get_attribute("href"))
driver.close()

# 再打开所有iframe查找全部的a标签
for iframe in soup.find_all('iframe'):
  url_ifr = iframe['src'] # 取得当前iframe的src属性值 
  rr = requests.get(url_ifr)
  rr.encoding = 'gb2312'
  soup_ifr = BeautifulSoup(rr.text,'lxml')
  for a in soup_ifr.find_all('a'):
    link = a['href']
    m = re.match(r'http:\/\/.*?(?=\/)',link)
    #print(link)
    if m:
      all_urls.add(m.group(0))