python利用beautifulSoup实现爬虫

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以前讲过利用phantomjs做爬虫抓网页 //www.jb51.net/article/55789.htm 是配合选择器做的

利用 beautifulSoup(文档 :http://www.crummy.com/software/BeautifulSoup/bs4/doc/)这个python模块,可以很轻松的抓取网页内容

            
# coding=utf-8
import urllib
from bs4 import BeautifulSoup

url ='http://www.baidu.com/s'
values ={'wd':'网球'}
encoded_param = urllib.urlencode(values)
full_url = url +'?'+ encoded_param
response = urllib.urlopen(full_url)
soup =BeautifulSoup(response)
alinks = soup.find_all('a')
          

上面可以抓取百度搜出来结果是网球的记录。

beautifulSoup内置了很多非常有用的方法。

几个比较好用的特性:

构造一个node元素

复制代码 代码如下:

soup = BeautifulSoup(' Extremely bold ')
tag = soup.b
type(tag)
#

属性可以使用attr拿到,结果是字典

复制代码 代码如下:

tag.attrs
# {u'class': u'boldest'}

或者直接tag.class取属性也可。

也可以自由操作属性

            
tag['class'] = 'verybold'
tag['id'] = 1
tag
# 
            
Extremely bold
del tag['class'] del tag['id'] tag #
Extremely bold
tag['class'] # KeyError: 'class' print(tag.get('class')) # None

还可以随便操作,查找dom元素,比如下面的例子

1.构建一份文档

            
html_doc = """

            
              The Dormouse's story
            
            

The Dormouse's story

Once upon a time there were three little sisters; and their names were Elsie , Lacie and Tillie ; and they lived at the bottom of a well.

...

""" from bs4 import BeautifulSoup soup = BeautifulSoup(html_doc)

2.各种搞

            
soup.head
# 
            
              The Dormouse's story
            
            
soup.title
# 
            
soup.body.b
# 
            
              The Dormouse's story
            
            
soup.a
# 
            
              Elsie
            
            
soup.find_all('a')
# [
            
              Elsie
            
            ,
# 
            
              Lacie
            
            ,
# 
            
              Tillie
            
            ]
head_tag = soup.head
head_tag
# 
            
              The Dormouse's story
            
            

head_tag.contents
[
            ]

title_tag = head_tag.contents[0]
title_tag
# 
            
title_tag.contents
# [u'The Dormouse's story']
len(soup.contents)
# 1
soup.contents[0].name
# u'html'
text = title_tag.contents[0]
text.contents

for child in title_tag.children:
  print(child)
head_tag.contents
# [
            ]
for child in head_tag.descendants:
  print(child)
# 
            
# The Dormouse's story

len(list(soup.children))
# 1
len(list(soup.descendants))
# 25
title_tag.string
# u'The Dormouse's story'
          

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