Python获取当前页面内所有链接的四种方法对比分析

'''
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=\').+?(?=\')" , r.text)
for link in matchs:
  print(link)
print()
# 利用 BeautifulSoup4 （DOM树）
soup = BeautifulSoup(r.text,'lxml')
for a in soup.find_all('a'):
  link = a['href']
  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))