Python BeautifulSoup 库基础使用

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
html5libBeautifulSoup(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

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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')
print(soup.prettify())
#对整个html进行格式化并输出
print(soup.title.string)
#求title节点的内容(文本)

标签选择器

优劣

  • 根据标签名(获取名称、属性、文本内容)、继承关系(children/descendants/parent/parents,这种继承返回结果为迭代器,需用enumerate来获取)选择元素
  • 优点:速度快
  • 缺点:对于标签名相同的标签,其属性值可能不同,这种方法无法筛选出目标标签

选择元素

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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')
print(soup.title)
#直接输出选择title
print(type(soup.title))
#输出title返回的数据类型
print(soup.head)
#输出head
print(soup.p)
#输出第一个p节点

获取名称

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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')
print(soup.title.name)
#输出title节点名

获取属性

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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')
print(soup.p.attrs['name'])
#用attrs[]获取p节点name属性的值
print(soup.p['name'])
#直接用[]获取name属性的值

获取内容

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html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p clss="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')
print(soup.p.string)
#输出打印第一个p节点的文本(内容)用string

嵌套选择

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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')
print(soup.head.title.string)
#输出head下子节点title节点的文本

节点

子节点和子孙节点

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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.p.contents)
#用contents可以获得p标签的子节点
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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.p.children)
#用children获取p的子节点
for i, child in enumerate(soup.p.children):
#用i,child表示以上获取结果的索引号与内容,用enumerate获取迭代器内容并进行遍历
print(i, child)
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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.p.descendants)
#输出打印p节点的孙子节点descendants
for i, child in enumerate(soup.p.descendants):
#用enumerate获取以上迭代器,用i,child分别表示索引号与内容,遍历它们并输出
print(i, child)

父节点和祖先节点

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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.a.parent)
#输出第一个a节点的父节点
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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(list(enumerate(soup.a.parents)))
#输出a节点父辈以上节点,用enumerate转换迭代器,最后将转换后的数据类型转换为list类型
# 观察得到索引号为2与3的结果一样,其中3的结果表示整个html文档

兄弟节点

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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(list(enumerate(soup.a.next_siblings)))
#获取第一个a节点之后的兄弟节点next_siblings,并用enumerate获取迭代器,最终转换成list类型
print(list(enumerate(soup.a.previous_siblings)))
#第一个a节点之前的兄弟节点previous_siblings,并用enumerate获取迭代器,最终转换成list类型

标准选择器

find_all 返回所有元素

  • 可根据标签名、属性、内容查找文档
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find_all( name , attrs , recursive , text , **kwargs )
  • name
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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'))
#查找并输出所有名为“ul”标签
print(type(soup.find_all('ul')[0]))
#输出第一个名为ul的标签
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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'):
#遍历输出所有ul节点下的li节点
print(ul.find_all('li'))
  • attrs
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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'}))
#用attrs属性参数以及key-value分别为id-list-1的数据来获取节点
print(soup.find_all(attrs={'name': 'elements'}))
#用attrs属性参数以及key-value分别为name-elements的数据来获取节点
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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'))
#直接用key=value的形式获取对应节点
print(soup.find_all(class_='element'))
#获取class='element'的节点
  • text
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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(text='Foo'))
#获取所有文本内容='Foo'的节点文本值,用text表示,

find 返回单个元素

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find( name , attrs , recursive , text , **kwargs )
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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('ul'))
print(type(soup.find('ul')))
#输出以上结果的数据类型
print(soup.find('page'))
#输出名为page的第一个节点

其他

  • find_parents()返回所有祖先节点,find_parent()返回直接父节点。
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find_parents()
find_parent()
  • 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。
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find_next_siblings()
find_next_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。
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find_previous_siblings() find_previous_sibling()
  • 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
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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
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find_all_next()
find_next()
  • 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
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find_all_previous()
find_previous()

CSS 选择器

  • 通过select()直接传入CSS选择器即可完成选择
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    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.select('.panel .panel-heading'))
#选择class属性为panel下子节点的class属性为panel-heading属性的节点,只有class属性才需要加.
print(soup.select('ul li'))
#选择所有ul节点下面的li节点
print(soup.select('#list-2 .element'))
#选择id为list-2,class为element的节点 ,用#表示id
print(type(soup.select('ul')[0]))
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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'):
#用select遍历ul的标签下的li标签,
print(ul.select('li'))

获取属性

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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'):
#用select获取所有ul标签,遍历所有ul标签的id属性的值
print(ul['id'])
#不用attrs
print(ul.attrs['id'])
#用attrs

获取内容

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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 li in soup.select('li'):
print(li.get_text())
#获取所有li标签的文本值

实例

requests类库请求网页获取响应内容

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import requests
#导入请求类库requests
newsurl = 'https://news.qq.com'
#将腾讯主页的url设为newsurl
res = requests.get(newsurl)
#根据newsurl请求获取响应内容,结果赋值为res
print(res.text)
#打印输出网页文本内容

BeautifulSoup 类库解析文档树

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from bs4 import BeautifulSoup
#导入bs4的BeautifulSoup类库
html_sample = ' \
<html> \
<body> \
<h1 id="title">Hello World</h1> \
<a href="#" class="link">This is link1</a> \
<a href="# link2" class="link">This is link2</a> \
</body> \
</html>'
soup = BeautifulSoup(html_sample,'html.parser')
#创建BeautifulSoup对象soup,利用html.parser解析器解析html_sample
soup.text
#输出打印soup的文本内容

找出含有特定的 html 标签

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soup.select('h1')[0].text
#利用select函数获取h1标签的文本内容
soup.select('a')[0].text
#利用select函数获取第一个a标签的文本内容
soup.select('a')[1].text
#利用select函数获取第二个a标签的文本内容
for alink in soup.select('a') :
print(alink.text)
#利用循环打印输出所有的a标签的文本内容,用alink表示循环变量名

找出含有特定的 CSS 属性

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soup.select('#title')[0].text
#找出id为title的属性所在节点的文本
soup.select('.link')[0].text
#找出class为link的第一个节点的文本

查找指定标签节点的某一属性

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for link in soup.select('a'):
#循环方式获取所有a标签,link表示循环变量名
print(link['href'])
#打印输出link的href属性值

获取腾讯新闻首页所有新闻的标题与详细内容页的 url

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import requests
from bs4 import BeautifulSoup
res = requests.get('http://news.qq.com/')
#get方式访问获取腾讯新闻首页(http://news.qq.com/)的响应体,结果命名为res
soup = BeautifulSoup(res.text,'html.parser')
#创建BeautifulSoup对象,利用html.parser对网页的文本内容进行解析
for news in soup.select('.Q-tpWrap.text'):
#利用开发者工具定位查找每条新闻的标题所在节点,news代表每个循环节点名
print(news.select('.linkto')[0].text,news.select('.linkto')[0]['href'])
#打印输出每条新闻的标题与url
print('===========')
#打印======进行间隔
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import requests
from bs4 import BeautifulSoup
res = requests.get('http://news.qq.com/')
#get方式访问获取腾讯新闻首页的响应体,结果命名为res
soup = BeautifulSoup(res.text, 'html.parser')
#创建BeautifulSoup对象,利用html.parser对网页的文本内容进行解析
newsary=[]
#定义newsary列表为空,用于存储所有新闻的标题与url
for news in soup.select('.Q-tpWrap .text'):
newsary.append({'title':news.select('.linkto')[0].text,'url':news.select('.linkto')[0]['href']})
#将用key为title,url分别保存每条新闻的标题与访问网址,并追加到newsary列表里面
  • 将newsary转换成dataFrame
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import pandas
newsdf = pandas.DataFrame(newsary)
newsdf
  • 将 newsdf 保存为 excel 文档,文件命名为 news
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newsdf.to_excel('news.xlsx')

总结

建议

  • 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