一、BeautifulSoup4的安装
方法一：cmd->easy_install BeautifulSoup
方法二：从http://www.crummy.com/software/BeautifulSoup/bs4/download/
下载->cmd->进入下载的文件目录->python setuyp.py install
二、 BeautifulSoup4的使用
1、导入
from bs4 import BeautifulSoup
注意：要是BeautifulSoup的版本为3.x，则导入方式为：from BeautifulSoup import BeautifulSoup
2、example
html文件：
html_doc = """
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.
...
"""
代码：
from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc)
接下来可以开始使用各种功能
soup.X (X为任意标签，返回整个标签，包括标签的属性，内容等）
如：soup.title
#
soup.p
#
The Dormouse's story
soup.a （注：仅仅返回第一个结果）
#
Elsie
soup.find_all('a') （find_all 可以返回所有）
# [Elsie,
#
Lacie,
#
Tillie]
find还可以按属性查找
soup.find(id="link3")
#
Tillie
要取某个标签的某个属性，可用函数有 find_all,get
for link in soup.find_all('a'):
print(link.get('href'))
# http://example.com/elsie
# http://example.com/lacie
# http://example.com/tillie
要取html文件中的所有文本，可使用get_text()
print(soup.get_text())
# 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.
# ...
如果是打开html文件，语句可用：
soup = BeautifulSoup(open("index.html"))
BeautifulSoup中的Object
tag （对应html中的标签）
tag.attrs (以字典形式返回tag的所有属性）
可以直接对tag的属性进行增、删、改，跟操作字典一样
tag['class'] = 'verybold'
tag['id'] = 1
tag
# <blockquote class="verybold" id="1">Extremely bold</blockquote>
del tag['class']
del tag['id']
tag
# <blockquote>Extremely bold</blockquote>
tag['class']
# KeyError: 'class'
print(tag.get('class'))
# None
X.contents (X为标签，可返回标签的内容）
eg.
head_tag = soup.head
head_tag
# <head><title>The Dormouse's story</title></head>
head_tag.contents
[<title>The Dormouse's story</title>]
title_tag = head_tag.contents[0]
title_tag
# <title>The Dormouse's story</title>
title_tag.contents
# [u'The Dormouse's story']
解决解析网页出现乱码问题：
import urllib2
2 from BeautifulSoup import BeautifulSoup
3
4 page = urllib2.urlopen('http://www.leeon.me');
5 soup = BeautifulSoup(page,fromEncoding="gb18030")
6
7 print soup.originalEncoding