BeautifulSoup库
一、简介
灵活又方便的网页解析库，处理高效，支持多种解析器。
利用它不用编写正则表达式即可方便地实现网页信息的提取。
二、详解
1.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 版本前中文容错能力弱 |
| 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，不依赖扩展 |
2.基本使用
html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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)3.标签选择器
3.1选择元素
html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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.title)
print(type(soup.title))
print(soup.head)
print(soup.p)如果一个标签存在多个，只返回第一个。
3.2获取名称
html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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.title.name)3.3获取属性
html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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.p.attrs['name'])
print(soup.p['name'])html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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.p.string)3.5嵌套选择
html = """<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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/else" class="sister" id="link1"><!--Elsie--></a>
<a href="http://example.com/lacle" class="sister" id="link2">Lacle</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.head.title.string)3.6子节点和子孙节点
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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.p.contents)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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.p.children)
for i,child in enumerate(soup.p.children):
print(i,child)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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.p.descendants)
for i,child in enumerate(soup.p.descendants):#所有的子孙节点
print(i,child)父节点和祖先节点
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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.a.parent)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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(list(enumerate(soup.a.parents)))#祖先节点兄弟节点
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 class="sister" href="http://example.com/else" id="link1">
<!--Elsie-->
</a>
<a class="sister" href="http://example.com/lacle" id="link2">
Lacle
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(list(enumerate(soup.a.next_siblings)))
print(list(enumerate(soup.a.previous_siblings)))标准选择器
find_all(name,attrs,recursive,text,**kwargs)可以根据标签名，属性，内容查找文档。
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'))#标签名name
print(type(soup.find_all('ul')[0]))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')
for ul in soup.find_all('ul'):
print(ul.find_all('li'))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'}))#属性attr
print(soup.find_all(attrs={'name':'elements'}))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(id='list-1'))#对于特殊类型的属性，可以直接这么写
print(soup.find_all(class_='element'))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(text='Foo'))#利用text进行选择find(name,attrs,recursive,text,**kwargs)返回单个元素，会返回列表里面第一个值。
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('ul'))
print(type(soup.find('ul')))
print(soup.find('page'))#不存在返回Nonefind_parents()#返回所有祖先节点
find_parent()#返回直接父节点
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()#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()#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()#返回节点前所有符合条件的节点
find_previous()#返回节点前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。
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.select('.panel .panel-heading')))
print(soup.select('ul li'))
print(soup.select('#list-2 .element'))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')
for ul in soup.select('ul'):
print(ul.select('li'))获取属性
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')
for ul in soup.select('ul'):
print(ul['id'])
print(ul.attrs['id'])获取内容
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')
for ul in soup.select('ul'):
print(li.get_text())总结
1.推荐使用lxml解析库，必要时使用html.parser
2.标签选择器筛选功能弱但是速度快。
3.建议使用find(),find_all()匹配单个结果或者多个结果。
4.如果对css选择器熟悉选择建议使用select()。
5.记住常用的获取属性和文本值的方法。