解析库
| 解析器 | 使用方法 | 优势 | 劣势 |
|---|---|---|---|
| Python标准库 | BeautifulSoup(markup, "html.parser") | Python的内置标准库、执行速度适中 、文档容错能力强 | Python 2.7.3 or 3.2.2)前的版本中文容错能力差 |
| lxml HTML 解析器 | BeautifulSoup(markup, "lxml") | 速度快、文档容错能力强 | 需要安装C语言库 |
| lxml XML 解析器 | BeautifulSoup(markup, "xml") | 速度快、唯一支持XML的解析器 | 需要安装C语言库 |
| html5lib | BeautifulSoup(markup, "html5lib") | 最好的容错性、以浏览器的方式解析文档、生成HTML5格式的文档 | 速度慢、不依赖外部扩展 |
基本使用
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<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">
<span>Elsie</span>
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.prettify())
print(soup.title.string)
标签选择器
选择元素
print(soup.title)
print(type(soup.title))
print(soup.head)
print(soup.p)
获取名称
print(soup.title.name)
title
获取属性
print(soup.p.attrs['name'])
print(soup.p['name'])
dromouse
dromouse
获取内容
print(soup.p.string)
The Dormouse's story
嵌套选择
print(soup.head.title.string)
The Dormouse's story
子节点和子孙节点
print(soup.p.contents)
['
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.
']
print(soup.p.children)
for i,child in enumerate(soup.p.children):
print(i,child)
父节点和祖先节点
print(soup.a.parent)
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.
print(list(enumerate(soup.a.parents)))
兄弟节点
print(list(enumerate(soup.a.next_siblings))
print(list(enumerate(soup.a.previous_siblings)))
[(0, '
'), (1, Lacie), (2, '
and
'), (3, Tillie), (4, '
and they lived at the bottom of a well.
')]
[(0, '
Once upon a time there were three little sisters; and their names were
')]
标准选择器
find_all(name,attrs,recursive,text,**kwargs)
可根据标签名、属性、内容查找文档
name
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<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('ul'))
print(type(soup.find_all('ul')[0]))
for ul in soup.find_all('ul'):
print(ul.find_all('li'))
attrs
print(soup.find_all(attrs={'id': 'list-1'}))
print(soup.find_all(attrs={'name': 'elements'}))
print(soup.find_all(id='list-1'))
print(soup.find_all(class_='element'))
text
print(soup.find_all(text='Foo'))
find( name , attrs , recursive , text , **kwargs )
find返回单个元素，find_all返回所有元素
print(soup.find('ul'))
print(type(soup.find('ul')))
print(soup.find('page'))
find_parents() find_parent()
find_parents()返回所有祖先节点，find_parent()返回直接父节点。
find_next_siblings() find_next_sibling()
find_next_siblings()返回后面所有兄弟节点，find_next_sibling()返回后面第一个兄弟节点。
find_previous_siblings() find_previous_sibling()
find_previous_siblings()返回前面所有兄弟节点，find_previous_sibling()返回前面第一个兄弟节点。
find_all_next() find_next()
find_all_next()返回节点后所有符合条件的节点, find_next()返回第一个符合条件的节点
find_all_previous() 和 find_previous()
find_all_previous()返回节点后所有符合条件的节点, find_previous()返回第一个符合条件的节点
CSS选择器
通过select()直接传入CSS选择器即可完成选择
print(soup.select('.panel .panel-heading'))
print(soup.select('ul li'))
print(soup.select('#list-2 .element'))
print(type(soup.select('ul')[0]))
[<div class="panel-heading">
<h4>Hello</h4>
</div>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
<class 'bs4.element.Tag'>
for ul in soup.select('ul'):
print(ul.select('li'))
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
for ul in soup.select('ul'):
print(ul['id'])
print(ul.attrs['id'])
list-1
list-1
list-2
list-2
获取内容
for li in soup.select('li'):
print(li.get_text())
Foo
Bar
Jay
Foo
Bar
总结
- 推荐使用lxml解析库，必要时使用html.parser
- 标签选择筛选功能弱但是速度快
- 建议使用find()、find_all()查询匹配单个结果或者多个结果
- 如果对CSS选择器熟悉建议使用select()
- 记住使用的获取属性和文本值得方法