BeautifulSoup库详解

时间 2021-05-13

标签 css html 浏览器函数 spa code orm xml htm three 栏目 CSS 繁體版

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什么是BeautifulSoup

Beautiful Soup 是一个能够从HTML或XML文件中提取数据的Python库.它可以经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.css

多看官方文档https://beautifulsoup.readthedocs.io/zh_CN/latest/html

经过例子来说解bs库的用法

from bs4 import BeautifulSoup  
  
html = '''  
<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,'lxml') //将代码进行格式化

output:  
 <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\>

详解bs4对html的解析

Tag

bs的使用和字典的使用极为类似,用.来进行运算浏览器

print(soup.title) 获取title标签(灵活变话:soup.a soup.li等

<title>The Dormouse's story</title>函数

print(soup.title.string) 获取title中的内容(能够灵活变化,得到其余标签中的内容)

The Dormouse's storyspa

print(soup.p["class"]) 获取class的值 (也能够灵活变换获取id或者data-id的值)

\['title'\]code

print(soup.find(id = 'link3')) 利用find函数找到相应的标签

bs能够屡次调用获得须要的标签内容orm

<p class\="title"\>  
 <b\>  
 The Dormouse's story  
 </b\>  
 </p\>  
   
 input:print(soup.p.b.string)  
 output: The Dormouse's story

find_all

find_all( name , attrs , recursive , string , **kwargs )xml

name: 根据标签名来进行查询(经常使用)htm
- soup.find_all('a') find_all返回的是一个列表,相应的能够soup.find_all('li')

经常使用方法是将列表中的元素提取出来进行处理  
alist = soup.find\_all('a')  
for a in alist:  
 function(a)

根据attrs来进行查询,用传入字典的方式来精准查询

html\='''  
<div class="panel">  
 <div class="panel-heading">  
 <h4>Hello</h4>  
 </div>  
 <div class="panel-body">  
 <ul class="list" id="list-1" name="elements">  
 <li class="element">Foo</li>  
 <li class="element">Bar</li>  
 <li class="element">Jay</li>  
 </ul>  
 <ul class="list list-small" id="list-2">  
 <li class="element">Foo</li>  
 <li class="element">Bar</li>  
 </ul>  
 </div>  
</div>  
'''  
from bs4 import BeautifulSoup  
soup = BeautifulSoup(html, 'lxml')  
print(soup.find\_all(attrs\={'id': 'list-1'}))  
print(soup.find\_all(attrs\={'name': 'elements'}))  
  
上面两句的output:  
\[<ul class\="list" id\="list-1" name\="elements"\>  
<li class\="element"\>Foo</li\>  
<li class\="element"\>Bar</li\>  
<li class\="element"\>Jay</li\>  
</ul\>\]

keyword参数

用tag的属性来进行搜索,搜索每一个tag的id属性three

soup.find_all(id = 'list-2')

class是特殊字,用下面方法进行处理

soup.find_all('',{"class":"element"})

按照CSS搜索

能够用class_ = ...... 来对class属性进行搜索新属性

soup.find_all("div",class_ = "panel-body")

谷歌浏览器快速得到标签CSS选择器方法

用选择器对组件选择---->找到相应的语句----->右键------>

能够根据须要进行copy,selector即为CSS的路径

find_all()若没有找到相应的数据返回一个空的列表

find()则返回一个None