Day1-python轻量级爬虫
爬虫：一段自动抓取互联网信息的程序。
从一个url出发访问与之关联的url 来获取目标 ；其价值在于：互联网数据，为我所用！
一个完整的爬虫架构：爬虫调度端{ url管理器，网页下载器，网页解析器}
下面是两个测试 ：
关于urllib2：
# -*- coding:utf8 -*-
'''
Created on 2020��1��9��
@author: long.19981105
'''
import http.cookiejar
import urllib.request
url="http://www.baidu.com"
print ('第一种方法')
resp = urllib.request.urlopen(url)
print (resp.getcode())
print(len(resp.read()))
print ('第二种方法')
request=urllib.request.Request(url)
request.add_header("user-agent","Mozilla/5.0")
resp2=urllib.request.urlopen(request)
print(resp2.getcode())
print(len(resp2.read()))
print ('第三种方法')
cj=http.cookiejar.CookieJar()
opener=urllib.request.build_opener(urllib.request.HTTPCookieProcessor(cj))
urllib.request.install_opener(opener)
resp3 = urllib.request.urlopen(url)
print (resp3.getcode())
print(cj)
关于bs4：
# -*- coding:utf8 -*-
'''
Created on 2020��1��9��
@author: long.19981105
'''
import urllib.request
import re
from bs4 import BeautifulSoup
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
soup=BeautifulSoup(html_doc,'html.parser',from_encoding='utf-8')
print('获取所有链接')
links=soup.find_all('a')
for link in links:
print(link.name,link['href'],link.get_text())
print('获取lacie的链接')
link_node=soup.find('a',href='http://example.com/lacie')
print (link_node.name,link_node['href'],link_node.get_text())
print('正则匹配')
link_node=soup.find('a',href=re.compile(r"ill"))
print(link_node.name,link_node['href'],link_node.get_text())
明天继续 给大家进行一个实战演练：：爬取百度百科1000个页面的数据
声明 本文为个人观看视频进行操作
