Beautiful Soup模块

Beautiful Soup 是一个可以从HTML或XML文件中提取数据的Python库,它能够通过你喜欢的转换器实现惯用的文档导航,查找,修改文档的方式.Beautiful Soup会帮你节省数小时甚至数天的工作时间.

快速开始，以如下html作为例子.

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>

"""

使用BeautifulSoup解析这段代码,能够得到一个 BeautifulSoup 的对象,并能按照标准的缩进格式的结构输出:

from bs4 import BeautifulSoup

soup = BeautifulSoup(html_doc,'html.parser')

print(soup.prettify())

<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 class="sister" href="http://example.com/elsie" id="link1">

    Elsie

   </a>

   ,

   <a class="sister" href="http://example.com/lacie" id="link2">

    Lacie

   </a>

   and

   <a class="sister" href="http://example.com/tillie" id="link3">

    Tillie

   </a>

   ;

and they lived at the bottom of a well.

  </p>

  <p class="story">

   ...

  </p>

 </body>

</html>

几个简单的浏览结构化数据的方法:

#打印出title标签的信息
soup.title

<title>The Dormouse's story</title>

#打印出title标签的标签名称

soup.title.name

'title'

#打印出title标签的内容

soup.title.string

"The Dormouse's story"

#打印出title标签的内存地址

soup.title.strings

<generator object _all_strings at 0x0000025B5572A780>

#打印出title标签的父标签

soup.title.parent.name

'head'

#打印出第一个p标签的信息

soup.p

<p class="title"><b>The Dormouse's story</b></p>

#取出p标签的值

soup.p['class'] 或者soup.p.get('class')

['title']

#打印出第一个a标签的信息

soup.a

<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>

#获取所有的a标签，返回一个列表.

soup.find_all('a')

[<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>]

#返回id=link3的的标签内容

soup.find(id='link3')

<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>

从文档中找到所有<a>标签的链接:

for link in soup.find_all('a'):

    print(link.get('href'))

http://example.com/elsie

http://example.com/lacie

http://example.com/tillie

从文档中获取所有文字内容:

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.

获取标签属性

soup.a.attrs

{'id': 'link1', 'class': ['sister'], 'href': 'http://example.com/elsie'}

使用BeautifulSoup库的 find()、findAll()和find_all()函数

在构造好BeautifulSoup对象后，借助find()和findAll()这两个函数，可以通过标签的不同属性轻松地把繁多的html内容过滤为你所想要的。

这两个函数的使用很灵活，可以：通过tag的id属性搜索标签、通过tag的class属性搜索标签、通过字典的形式搜索标签内容返回的为一个列表、通过正则表达式匹配搜索等等

基本使用格式：

通过tag的id属性搜索标签

t = soup.find(attrs={"id":"aa"})

搜索a标签中class属性是sister的所有标签内容

t= soup.findAll('a',{'class':'sister'})

find_all() 方法搜索当前tag的所有tag子节点,并判断是否符合过滤器的条件.

soup.find_all("title")

# [<title>The Dormouse's story</title>]

soup.find_all("p", "title")

# [<p class="title"><b>The Dormouse's story</b></p>]

soup.find_all("a")

# [<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>,

#  <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>,

#  <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>]

soup.find_all(id="link2")

# [<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>]

BeautifulSoup的使用

在用requests库从网页上得到了网页数据后，就要开始使用BeautifulSoup了。

一个示例：

#!/usr/bin/python

#coding:utf-

import requests

from bs4 import BeautifulSoup

url = requests.get("http://www.douban.com/tag/%E5%B0%8F%E8%AF%B4/?focus=book")

#获取页面代码

#print(url.text)

#创建BeautifulSoup对象

soup = BeautifulSoup(url.text,"html.parser")

#print(soup.prettify())

#book_div 查找出div标签中id属性是book的内容

book_div = soup.find('div',{'id':'book'})

#print(book_div)

#book_div的另一种写法，获取结果一样

# book_div = soup.find(attrs={"id":"book"})

# print('book_div的内容',book_div)

#通过class="title"获取所有的book  a标签

book_a = book_div.findAll(attrs={"class":"title"})

print(book_a)

#

# for循环是遍历book_a所有的a标签,book.string是输出a标签中的内容.

for book in book_a:

    print(book.string)

执行结果：

Beautiful Soup模块

参考文档： https://www.cnblogs.com/sunnywss/p/6644542.html

　　　　　https://www.cnblogs.com/dan-baishucaizi/p/8494913.html

　　　　 http://www.cnblogs.com/hearzeus/p/5151449.html

https://beautifulsoup.readthedocs.io/zh_CN/v4.4.0/

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Beautiful Soup模块

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