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BeautifulSoup的基本使用

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在这里插入图片描述

bs4

bs4的安装

要使用BeautifulSoup4需要先安装lxml,再安装bs4

pip install lxml

pip install bs4

使用方法：

from bs4 import BeautifulSoup

lxml和bs4对比学习

from lxml import etree
tree = etree.HTML(html)
tree.xpath()

from bs4 import BeautifulSoup
soup =  BeautifulSoup(html_doc,'lxml')

注意事项：
创建soup对象时如果不传’lxml’或者features="lxml"会出现以下警告
在这里插入图片描述

bs4的快速入门

解析器的比较(了解即可)

解析器用法优点缺点python标准库BeautifulSoup(markup,‘html.parser’)python标准库，执行速度适中(在python2.7.3或3.2.2之前的版本中)文档容错能力差lxml的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的XML解析器BeautifulSoup(markup,‘lxml-xml’)或者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

对象种类

Tag：标签
BeautifulSoup：bs对象
NavigableString：可导航的字符串
Comment：注释

from bs4 import BeautifulSoup

# 创建模拟HTML代码的字符串
html_doc ="""
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><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>

<span><!--comment注释内容举例--></span>
"""# 创建soup对象
soup = BeautifulSoup(html_doc,'lxml')print(type(soup.title))# <class 'bs4.element.Tag'>print(type(soup))# <class 'bs4.BeautifulSoup'>print(type(soup.title.string))# <class 'bs4.element.NavigableString'>print(type(soup.span.string))# <class 'bs4.element.Comment'>

bs4的简单使用

获取标签内容

from bs4 import BeautifulSoup

# 创建模拟HTML代码的字符串
html_doc ="""
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><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>
</body>
</html>
"""# 创建soup对象
soup = BeautifulSoup(html_doc,'lxml')print('head标签内容:\n', soup.head)# 打印head标签print('body标签内容:\n', soup.body)# 打印body标签print('html标签内容:\n', soup.html)# 打印html标签print('p标签内容:\n', soup.p)# 打印p标签

✅注意：在打印p标签对应的代码时，可以发现只打印了第一个p标签内容，这时我们可以通过find_all来获取p标签全部内容

print('p标签内容:\n', soup.find_all('p'))

✅这里需要注意使用find_all里面必须传入的是字符串
获取标签名字
通过name属性获取标签名字

from bs4 import BeautifulSoup

# 创建模拟HTML代码的字符串
html_doc ="""
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><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>
</body>
</html>
"""# 创建soup对象
soup = BeautifulSoup(html_doc,'lxml')print('head标签名字:\n', soup.head.name)# 打印head标签名字print('body标签名字:\n', soup.body.name)# 打印body标签名字print('html标签名字:\n', soup.html.name)# 打印html标签名字print('p标签名字:\n', soup.find_all('p').name)# 打印p标签名字

✅如果要找到两个标签的内容，需要传入列表过滤器，而不是字符串过滤器
使用字符串过滤器获取多个标签内容会返回空列表

print(soup.find_all('title','p'))

[]

需要使用列表过滤器获取多个标签内容

print(soup.find_all(['title','p']))

[<title>The Dormouse's story</title>, <p class="title"><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>]

获取a标签的href属性值

from bs4 import BeautifulSoup

# 创建模拟HTML代码的字符串
html_doc ="""
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><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>
"""# 创建soup对象
soup = BeautifulSoup(html_doc,'lxml')
a_list = soup.find_all('a')# 遍历列表取属性值for a in a_list:# 第一种方法通过get去获取href属性值(没有找到返回None)print(a.get('href'))# 第二种方法先通过attrs获取所有属性值，再提取出你想要的属性值print(a.attrs['href'])# 第三种方法获取没有的属性值会报错print(a['href'])

✅扩展：使用prettify()美化 让节点层级关系更加明显 方便分析

print(soup.prettify())

不使用prettify时的代码

<html><head><title>The Dormouse's story</title></head><body><p class="title"><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>

使用prettify时的代码

<html><head><title>
   The Dormouse's story
  </title></head><body><p class="title"><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>

遍历文档树

from bs4 import BeautifulSoup

# 创建模拟HTML代码的字符串
html_doc ="""
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title"><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>
</body>
</html>
"""
soup = BeautifulSoup(html_doc,'lxml')
head = soup.head
# contents返回的是所有子节点的列表 [<title>The Dormouse's story</title>]print(head.contents)# children返回的是一个子节点的迭代器 <list_iterator object at 0x00000264BADC2748>print(head.children)# 凡是迭代器都是可以遍历的for h in head.children:print(h)
html = soup.html  # 会把换行也当作子节点匹配到# descendants 返回的是一个生成器遍历子子孙孙  <generator object Tag.descendants at 0x0000018C15BFF4C8>print(html.descendants)# 凡是生成器都是可遍历的for h in html.descendants:print(h)'''
需要重点掌握的
string获取标签里面的内容
strings 返回是一个生成器对象用过来获取多个标签内容
stripped_strings 和strings基本一致 但是它可以把多余的空格去掉
'''print(soup.title.string)print(soup.html.string)# 返回生成器对象<generator object Tag._all_strings at 0x000001AAFF9EF4C8># soup.html.strings 包含在html标签里面的文本都会被获取到print(soup.html.strings)for h in soup.html.strings:print(h)# stripped_strings可以把多余的空格去掉# 返回生成器对象<generator object PageElement.stripped_strings at 0x000001E31284F4C8>print(soup.html.stripped_strings)for h in soup.html.stripped_strings:print(h)'''
parent直接获得父节点
parents获取所有的父节点
'''
title = soup.title
# parent找直接父节点print(title.parent)# parents获取所有父节点# 返回生成器对象<generator object PageElement.parents at 0x000001F02049F4C8>print(title.parents)for p in title.parents:print(p)# html的父节点就是整个文档print(soup.html.parent)# <class 'bs4.BeautifulSoup'>print(type(soup.html.parent))
案例练习

获取所有职位名称

html ="""
<table class="tablelist" cellpadding="0" cellspacing="0">
    <tbody>
        <tr class="h">
            <td class="l" width="374">职位名称</td>
            <td>职位类别</td>
            <td>人数</td>
            <td>地点</td>
            <td>发布时间</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=33824&keywords=python&tid=87&lid=2218">22989-金融云区块链高级研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=29938&keywords=python&tid=87&lid=2218">22989-金融云高级后台开发</a></td>
            <td>技术类</td>
            <td>2</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31236&keywords=python&tid=87&lid=2218">SNG16-腾讯音乐运营开发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>2</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31235&keywords=python&tid=87&lid=2218">SNG16-腾讯音乐业务运维工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=34531&keywords=python&tid=87&lid=2218">TEG03-高级研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=34532&keywords=python&tid=87&lid=2218">TEG03-高级图像算法研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31648&keywords=python&tid=87&lid=2218">TEG11-高级AI开发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>4</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=32218&keywords=python&tid=87&lid=2218">15851-后台开发工程师</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=32217&keywords=python&tid=87&lid=2218">15851-后台开发工程师</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a id="test" class="test" target='_blank' href="position_detail.php?id=34511&keywords=python&tid=87&lid=2218">SNG11-高级业务运维工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
    </tbody>
</table>
"""
思路

不难看出想要的数据在tr节点的a标签里，只需要遍历所有的tr节点，从遍历出来的tr节点取a标签里面的文本数据

代码实现
from bs4 import BeautifulSoup

html ="""
<table class="tablelist" cellpadding="0" cellspacing="0">
    <tbody>
        <tr class="h">
            <td class="l" width="374">职位名称</td>
            <td>职位类别</td>
            <td>人数</td>
            <td>地点</td>
            <td>发布时间</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=33824&keywords=python&tid=87&lid=2218">22989-金融云区块链高级研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=29938&keywords=python&tid=87&lid=2218">22989-金融云高级后台开发</a></td>
            <td>技术类</td>
            <td>2</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31236&keywords=python&tid=87&lid=2218">SNG16-腾讯音乐运营开发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>2</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31235&keywords=python&tid=87&lid=2218">SNG16-腾讯音乐业务运维工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-25</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=34531&keywords=python&tid=87&lid=2218">TEG03-高级研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=34532&keywords=python&tid=87&lid=2218">TEG03-高级图像算法研发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=31648&keywords=python&tid=87&lid=2218">TEG11-高级AI开发工程师（深圳）</a></td>
            <td>技术类</td>
            <td>4</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a target="_blank" href="position_detail.php?id=32218&keywords=python&tid=87&lid=2218">15851-后台开发工程师</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="even">
            <td class="l square"><a target="_blank" href="position_detail.php?id=32217&keywords=python&tid=87&lid=2218">15851-后台开发工程师</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
        <tr class="odd">
            <td class="l square"><a id="test" class="test" target='_blank' href="position_detail.php?id=34511&keywords=python&tid=87&lid=2218">SNG11-高级业务运维工程师（深圳）</a></td>
            <td>技术类</td>
            <td>1</td>
            <td>深圳</td>
            <td>2017-11-24</td>
        </tr>
    </tbody>
</table>
"""# 创建soup对象
soup = BeautifulSoup(html,'lxml')# 使用find_all()找到所有的tr节点(经过观察第一个tr节点为表头,忽略不计)
tr_list = soup.find_all('tr')[1:]# 遍历tr_list取a标签里的文本数据for tr in tr_list:
    a_list = tr.find_all('a')print(a_list[0].string)

运行结果如下：

22989-金融云区块链高级研发工程师（深圳）
22989-金融云高级后台开发
SNG16-腾讯音乐运营开发工程师（深圳）
SNG16-腾讯音乐业务运维工程师（深圳）
TEG03-高级研发工程师（深圳）
TEG03-高级图像算法研发工程师（深圳）
TEG11-高级AI开发工程师（深圳）
15851-后台开发工程师
15851-后台开发工程师
SNG11-高级业务运维工程师（深圳）

🔥以上就是bs4的基本使用，如果有改进的建议，欢迎在评论区留言奥~

在这里插入图片描述

标签： python pycharm BeautifulSoup
本文转载自: https://blog.csdn.net/xqe777/article/details/123588660
版权归原作者 honker707 所有， 如有侵权，请联系我们删除。
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