• Python爬虫【解析库之beautifulsoup】

    解析库的安装

    pip3 install beautifulsoup4

    初始化 BeautifulSoup(str,"解析库")

    from bs4 import BeautifulSoup

    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>
    '''

    soup = BeautifulSoup(html,"lxml") # soup = BeautifulSoup(html,"html.parser")

    标签选择器

    选择元素 soup.E

    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)
print(type(soup.title))
print(soup.head)
print(soup.p)

"""
打印结果:
<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>
"""
    选择元素

    获取名称 soup.E.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/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) # title
    获取名称

    获取属性  soup.E.attrs[ ]  or  soup.E[ ]

    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'])
print(soup.p['name'])
"""
dromouse
dromouse
"""
    获取属性

    获取内容 soup.E.string

    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)
"""
The Dormouse's story
"""
    获取内容

    嵌套选择 soup.E.E

    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)
"""
The Dormouse's story
"""
    View Code

    子节点 soup.E.contents

     1 html = """
 2 <html>
 3     <head>
 4         <title>The Dormouse's story</title>
 5     </head>
 6     <body>
 7         <p class="story">
 8             Once upon a time there were three little sisters; and their names were
 9             <a href="http://example.com/elsie" class="sister" id="link1">
10                 <span>Elsie</span>
11             </a>
12             <a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> 
13             and
14             <a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>
15             and they lived at the bottom of a well.
16         </p>
17         <p class="story">...</p>
18 """
19 from bs4 import BeautifulSoup
20 soup = BeautifulSoup(html, 'lxml')
21 print(soup.p.contents)
22 """
23 ['
            Once upon a time there were three little sisters; and their names were
            ', <a class="sister" href="http://example.com/elsie" id="link1">
24 <span>Elsie</span>
25 </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.
        ']
26 
27 """
    View Code

    子节点 soup.E.children

    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)
for i, child in enumerate(soup.p.children):
    print(i, child)
"""
<list_iterator object at 0x00B116D0>
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.
"""
    View Code

    子孙节点 soup.E.descendants 包括标签里面的文本都属于

    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)
for i, child in enumerate(soup.p.descendants):
    print(i, child)
"""
<generator object descendants at 0x03EBD420>
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.
"""
    View Code

    父节点 soup.E.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 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)
    View Code

    祖先节点 soup.E.parents

    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)))
    View Code

    兄弟节点 soup.E.next_siblings  soup.E.previous_siblings

    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)))
print(list(enumerate(soup.a.previous_siblings)))
    View Code

    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

    标签名获取 soup.find_all('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'))
    View Code

    属性获取 soup.find_all(attrs={})

    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'}))
    View Code
    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'))
print(soup.find_all(class_='element'))
    第二种

    文本内容获取

    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'))
    View Code

    find( name , attrs , recursive , text , **kwargs )

    find返回单个元素，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')
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 soup.select(css选择器)

    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'))
print(soup.select('ul li'))
print(soup.select('#list-2 .element'))
print(type(soup.select('ul')[0]))
    View Code
    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.select('li'))
    View Code

    获取属性 E.attrs[] or  E[]

    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'])
    print(ul.attrs['id'])
    View Code

    获取内容 get_text()

    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())
    View Code

    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

    本文代码皆来自崔庆才《Python3网络爬虫开发实战》
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  • 原文地址：https://www.cnblogs.com/tangkaishou/p/9541231.html
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