python爬虫简单架构原理及示例

网页下载器示例：

# coding:utf-8
import urllib2
import cookielib
url = "http://www.baidu.com"

print u"第一种方法"
# pip install urllib2
response1 = urllib2.urlopen(url)
print response1.getcode()
print len(response1.read())

print u"第二种方法"
request = urllib2.Request(url)
# 把爬虫伪装成浏览器
request.add_header("user-agent", "Mozilla/5.0")
response2 = urllib2.urlopen(request)
print response2.getcode()
print len(response2.read())

print u"第三种方法"
# pip install cookielib
cj = cookielib.CookieJar()
opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))
urllib2.install_opener(opener)
response3 = urllib2.urlopen(request)
print response3.getcode()
print cj
print len(response3.read())

# 运行结果

beautifulsoap使用示例

#coding:utf-8

# 安装beautifulsoap4  D:\Python27\Lib>pip install beautifulsoup4

from bs4 import BeautifulSoup
import re

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 u'获取所有的链接'
links = soup.find_all('a')

for link in links:
    print link.name,link['href'], link.get_text()

print u'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 u'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()

print u'获取p段落名字'
link_node = soup.find('p', class_="title")
print link_node.name, link_node.get_text()

python爬虫简单架构原理及示例

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