1.BeautifulSoup的介绍
BeautifulSop是一个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就可以方便的实现网页信息的提取。
2.安装BeautifulSoup
已经更新到第4个版本,所以是beautifulsoup4,使用cmd命令安装,前提安装的anaconda,并且环境变量配置正确。
cmd命令: pip3 install beautifulsoup4
3.BeautifulSoup用法详解
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 | Python2.7.3 or 3.2.2前的版本中文容错能力差 |
lxml HTML | 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 | 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 |
4.基本使用
# 定义一个不完整的html代码文本,html和body标签为闭合的残缺文本
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/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>
"""
# 导入库
from bs4 import BeautifulSoup
# 使用BeautifulSoup对指定的html文档,并指定解析器进行解析,"lxml”解析器速度快,容错能力强
soup = BeautifulSoup(html,"lxml")
# 进行容错补全标签,进行修正
print(soup.prettify())
# 提取容错后的title标签中的内容
print(soup.title.string)
<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 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>
The Dormouse's story
标签选择器的使用
5.标签选择器
# 选择元素,获取标签及标签的所有内容
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/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>
"""
# 导入库
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,"lxml")
# 选择title标签的内容
print(soup.title)
# 输出title标签的类型,是一个 Tag对象类型
print(type(soup.title))
# 提取head标签中的内容,也是一个tag对象类型
print(soup.head)
# p标签有多个内容默认提取第一个p标签的内容
print(soup.p)
<title>The Dormouse's story</title>
<class 'bs4.element.Tag'>
<head><title>The Dormouse's story</title></head>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
6.获取标签的名称
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/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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# 获取tilte标签的name值,也就是标签名
print(soup.title.name)
title
7.获取标签内的属性的值
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/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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'xml')
# 获取p标签中属性名为name的值
print(soup.p.attrs['name'])
# 另一种语法格式
print(soup.p['name'])
dromouse
dromouse
8.获取标签内的内容
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/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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# 获取标签内的内容
print(soup.p.string)
The Dormouse's story
9.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/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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# 使用.号层层递进进行选择
print(soup.head.title.string)
The Dormouse's story
10.获取指定标签的所有内容
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')
# 以列表的形式返回p标签下的所有内容,包括子节点和子孙节点
print(soup.p.contents)
['\n Once upon a time there were three little sisters; and their names were\n ', <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>, '\n', <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, ' \n and\n ', <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>, '\n and they lived at the bottom of a well.\n ']
11.使用迭代器获取指定标签的子节点
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 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')
# 获取到对应标签子节点的迭代器对象
print(soup.p.children)
# 通过枚举,再遍历,输出子节点的内容
# for 子节点索引变量,子节点的对象变量
for i, child in enumerate(soup.p.children):
print(i,child)
<list_iterator object at 0x0000023C138E18D0>
0
Once upon a time there were three little sisters; and their names were
1 <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
2
3 <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
4
and
5 <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
6
and they lived at the bottom of a well.
14.获取指定标签的子节点及子孙节点
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 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')
# 使用descendants获取子节点及孙子节点的迭代器对象
print(soup.p.descendants)
for i, child in enumerate(soup.p.descendants):
print(i, child)
<generator object descendants at 0x0000023C138F97D8>
0
Once upon a time there were three little sisters; and their names were
1 <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
2
3 <span>Elsie</span>
4 Elsie
5
6
7 <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
8 Lacie
9
and
10 <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
11 Tillie
12
and they lived at the bottom of a well.
15 父节点
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 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")
# 获取到第一个a标签的符节点标签,并把标签及内容所有输出
print(soup.a.parent)
<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">
<span>Elsie</span>
</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>
16.父节点和所有的祖先节点
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 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')
# 使用parents获取到所有的祖先节点和父节点的迭代器
# 使用list构造成列表输出,结果先获取父节点,
# 再获取父节点的父节点,最后再次输出一遍html整个文档
print(list(enumerate(soup.a.parents)))
[(0, <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">
<span>Elsie</span>
</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>), (1, <body>
<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">
<span>Elsie</span>
</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>), (2, <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/elsie" id="link1">
<span>Elsie</span>
</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>), (3, <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/elsie" id="link1">
<span>Elsie</span>
</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>)]
17.兄弟节点
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<p class="story">
<b href="http://example.com/lacie" class="sister" id="link2">Lacie</b>
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>
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')
# 获取指定标签的所有后兄弟节点
# print(list(enumerate(soup.a.next_siblings)))
# 获取指定标签的所有前兄弟节点
print(list(enumerate(soup.a.previous_siblings)))
[(0, '\n Once upon a time there were three little sisters; and their names were\n '), (1, <b class="sister" href="http://example.com/lacie" id="link2">Lacie</b>), (2, '\n')]
18 标准选择器
由于html中还包含其他属性,所以标签选择器不能满足要求,还要使用标准选择器才能提取以下特殊的属性。
标准选择器find_all方法和正则表达式的结果是一的工作原理,从目标文本中找出满足条件的所有字符串,构成一个列表。
find_all(name,attrs,recursive,text,**kwargs)
此方法可以根据标签名,属性,内容查找文档
# 根据naem(标签名)来查找文档中的内容
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')
# 使用find_all(标签名)来查找满足条件的内容
# 以列表的方式返回内容
print(soup.find_all('ul'))
# 测列表中的一个内容的类型,是bs4.element.Tag标签类型
print(type(soup.find_all('ul')[0]))
[<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>]
<class 'bs4.element.Tag'>
19 使用标准选择器中的attrs指定属性查找文档内容
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')
# 使用find_all(指定属性传入一个字典数据,字典的键就是html中的属性的名字,字典的值就是
# 属性的值)
print(soup.find_all(attrs={'id': 'list-1'}))
# 同样可以使用同一个标签的其他属性与对应的值查找内容
print(soup.find_all(attrs={'name': 'elements'}))
[<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" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
20 另一种格式的写法,直接在find_all(属性名=属性值),不需要写attrs
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(id='list-1'))
# 注意:使用class属性时,要加下划线 "class_",因为"class"在python中是一个关键字
print(soup.find_all(class_='element'))
[<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
[<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>]
21 在find._all方法中使用text属性来指定标签中的文本,查找内容
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')
# 结果输出html满足条件的字符串列表
print(soup.find_all(text='Foo'))
['Foo', 'Foo']
- find(name,attrs,recursive,text,/*/*kwargs)
此方法返回匹配条件的第一个元素,而find_all返回所有元素
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')
# 返回指定标签名的所有内容及标签
print(soup.find('ul'))
# 返回的类型是一个Tag类型
print(type(soup.find('ul')))
# 返回的是None,因为html文档中没有这个标签
print(soup.find('page'))
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<class 'bs4.element.Tag'>
None
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
19 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">
<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')
# CSS选择器中,.号代表class, # 号代表 id
# 下面查找class=anel空格 再在其中找class=panel-heading的标签的所有内容及标签
# 也可以多次调用select层层递进选择嵌套中的内容
print(soup.select('.panel .panel-heading'))
# 下面使用指定标签的方法,查找ul标签下面li标签的所有元素,以列表方式返回
print(soup.select('ul li'))
# 使用# 号指定id=list-2然后空格, 使用.指定class=element的标签所有内容及标签本身
print(soup.select('#list-2 .element'))
# f返回按照标签选择器选中的列表第一个员的type
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'>
20 使用CSS选择器获取属性
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<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'])
# 也可以使用attrs['属性名']
print(ul.attrs['id'])
list-1
list-1
list-2
list-2
21 使用CSS选择器获取文本
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')
# 获取到li标签列表并遍历
for li in soup.select('li'):
# 获取对应标签中的文本
print(li.get_text())
Foo
Bar
Jay
Foo
Bar
22 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()
记住常用的获取属性和文本值的方法