Python爬虫库BeautifulSoup的介绍与简单使用实例


Posted in Python onJanuary 25, 2020

一、介绍

BeautifulSoup库是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。

Python常用解析库

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
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

二、快速开始

给定html文档,产生BeautifulSoup对象

from bs4 import BeautifulSoup
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" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>

<p class="story">...</p>
"""
soup = BeautifulSoup(html_doc,'lxml')

输出完整文本

print(soup.prettify())
<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" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1">
  Elsie
  </a>
  ,
  <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">
  Lacie
  </a>
  and
  <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">
  Tillie
  </a>
  ;
and they lived at the bottom of a well.
 </p>
 <p class="story">
  ...
 </p>
 </body>
</html>

浏览结构化数据

print(soup.title) #<title>标签及内容
print(soup.title.name) #<title>name属性
print(soup.title.string) #<title>内的字符串
print(soup.title.parent.name) #<title>的父标签name属性(head)
print(soup.p) # 第一个<p></p>
print(soup.p['class']) #第一个<p></p>的class
print(soup.a) # 第一个<a></a>
print(soup.find_all('a')) # 所有<a></a>
print(soup.find(id="link3")) # 所有id='link3'的标签
<title>The Dormouse's story</title>
title
The Dormouse's story
head
<p class="title"><b>The Dormouse's story</b></p>
['title']
<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1">Elsie</a>
[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1">Elsie</a>, <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>]
<a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>

找出所有标签内的链接

for link in soup.find_all('a'):
  print(link.get('href'))
http://example.com/elsie
http://example.com/lacie
http://example.com/tillie

获得所有文字内容

print(soup.get_text())
The Dormouse's story

The Dormouse's story
Once upon a time there were three little sisters; and their names were
Elsie,
Lacie and
Tillie;
and they lived at the bottom of a well.
...

自动补全标签并进行格式化

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" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" 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')#传入解析器:lxml
print(soup.prettify())#格式化代码,自动补全
print(soup.title.string)#得到title标签里的内容

标签选择器

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/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" 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')#传入解析器:lxml
print(soup.title)#选择了title标签
print(type(soup.title))#查看类型
print(soup.head)

获取标签名称

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.title.name)

获取标签属性

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.p.attrs['name'])#获取p标签中,name这个属性的值
print(soup.p['name'])#另一种写法,比较直接

获取标签内容

print(soup.p.string)

标签嵌套选择

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.head.title.string)

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 href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1">
        <span>Elsie</span>
      </a>
      <a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> 
      and
      <a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" 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')#传入解析器:lxml
print(soup.p.contents)#获取指定标签的子节点,类型是list

另一个方法,child:

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.p.children)#获取指定标签的子节点的迭代器对象
for i,children in enumerate(soup.p.children):#i接受索引,children接受内容
	print(i,children)

输出结果与上面的一样,多了一个索引。注意,只能用循环来迭代出子节点的信息。因为直接返回的只是一个迭代器对象。

获取子孙节点:

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.p.descendants)#获取指定标签的子孙节点的迭代器对象
for i,child in enumerate(soup.p.descendants):#i接受索引,child接受内容
	print(i,child)

父节点和祖先节点

parent

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(soup.a.parent)#获取指定标签的父节点

parents

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(list(enumerate(soup.a.parents)))#获取指定标签的祖先节点

兄弟节点

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')#传入解析器:lxml
print(list(enumerate(soup.a.next_siblings)))#获取指定标签的后面的兄弟节点
print(list(enumerate(soup.a.previous_siblings)))#获取指定标签的前面的兄弟节点

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。

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'))#查找所有ul标签下的内容
print(type(soup.find_all('ul')[0]))#查看其类型

下面的例子就是查找所有ul标签下的li标签:

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.find_all('ul'):
  print(ul.find_all('li'))

attrs(属性)

通过属性进行元素的查找

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'}))#传入的是一个字典类型,也就是想要查找的属性
print(soup.find_all(attrs={'name': 'elements'}))

查找到的是同样的内容,因为这两个属性是在同一个标签里面的。

特殊类型的参数查找:

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(id='list-1'))#id是个特殊的属性,可以直接使用
print(soup.find_all(class_='element')) #class是关键字所以要用class_

text

根据文本内容来进行选择:

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')
print(soup.find_all(text='Foo'))#查找文本为Foo的内容,但是返回的不是标签

所以说这个text在做内容匹配的时候比较方便,但是在做内容查找的时候并不是太方便。

方法

find

find用法和findall一模一样,但是返回的是找到的第一个符合条件的内容输出。

ind_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()返回后面的所有兄弟节点,find_next_sibling()返回后面的第一个兄弟节点

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()返回后面第一个符合条件的节点

find_all_previous(),find_previous()

find_all_previous()返回节点前所有符合条件的节点,find_previous()返回前面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">
      <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'))#.代表class,中间需要空格来分隔
print(soup.select('ul li')) #选择ul标签下面的li标签
print(soup.select('#list-2 .element')) #'#'代表id。这句的意思是查找id为"list-2"的标签下的,class=element的元素
print(type(soup.select('ul')[0]))#打印节点类型

再看看层层嵌套的选择:

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
	print(ul.select('li'))

获取属性

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
  print(ul['id'])# 用[ ]即可获取属性
  print(ul.attrs['id'])#另一种写法

获取内容

from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for li in soup.select('li'):
  print(li.get_text())

用get_text()方法就能获取内容了。

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

更多关于Python爬虫库BeautifulSoup的介绍与简单使用实例请点击下面的相关链接

Python 相关文章推荐
Python实现的几个常用排序算法实例
Jun 16 Python
Python读写配置文件的方法
Jun 03 Python
在Linux系统上部署Apache+Python+Django+MySQL环境
Dec 24 Python
Python编程实现正则删除命令功能
Aug 30 Python
Python使用当前时间、随机数产生一个唯一数字的方法
Sep 18 Python
Django框架登录加上验证码校验实现验证功能示例
May 23 Python
python爬取百度贴吧前1000页内容(requests库面向对象思想实现)
Aug 10 Python
Python定义函数时参数有默认值问题解决
Dec 19 Python
代码总结Python2 和 Python3 字符串的区别
Jan 28 Python
Python xpath表达式如何实现数据处理
Jun 13 Python
python 实现图片修复(可用于去水印)
Nov 19 Python
Python中Selenium对Cookie的操作方法
Jul 09 Python
使用Python爬虫库requests发送表单数据和JSON数据
Jan 25 #Python
Python爬虫库requests获取响应内容、响应状态码、响应头
Jan 25 #Python
使用Python爬虫库requests发送请求、传递URL参数、定制headers
Jan 25 #Python
flask框架自定义url转换器操作详解
Jan 25 #Python
常用python爬虫库介绍与简要说明
Jan 25 #Python
flask框架url与重定向操作实例详解
Jan 25 #Python
flask框架蓝图和子域名配置详解
Jan 25 #Python
You might like
Fleaphp常见函数功能与用法示例
2016/11/15 PHP
PHP magento后台无法登录问题解决方法
2016/11/24 PHP
PHP微信PC二维码登陆的实现思路
2017/07/13 PHP
YUI 读码日记之 YAHOO.lang.is*
2008/03/22 Javascript
javascript跨域的4种方法和原理详解
2014/04/08 Javascript
[将免费进行到底]在Amazon的一年免费服务器上安装Node.JS, NPM和OurJS博客
2014/08/18 Javascript
node.js中的fs.mkdirSync方法使用说明
2014/12/17 Javascript
js实现显示当前状态的导航效果代码
2015/08/28 Javascript
js去字符串前后空格的实现方法
2016/02/26 Javascript
基于Javascript实现返回顶部按钮
2016/02/29 Javascript
easyUI实现(alert)提示框自动关闭的实例代码
2016/11/07 Javascript
详解vuelidate 对于vueJs2.0的验证解决方案
2017/03/09 Javascript
JavaScript实现打地鼠小游戏
2020/04/23 Javascript
通过命令行生成vue项目框架的方法
2017/07/12 Javascript
JS实现留言板功能[楼层效果展示]
2017/12/27 Javascript
vue router 用户登陆功能的实例代码
2019/04/24 Javascript
jQuery实现二级导航菜单的示例
2020/09/30 jQuery
[01:14:34]DOTA2上海特级锦标赛C组资格赛#2 LGD VS Newbee第一局
2016/02/28 DOTA
python切换hosts文件代码示例
2013/12/31 Python
Python递归实现汉诺塔算法示例
2018/03/19 Python
[原创]Python入门教程3. 列表基本操作【定义、运算、常用函数】
2018/10/30 Python
python对列进行平移变换的方法(shift)
2019/01/10 Python
对python过滤器和lambda函数的用法详解
2019/01/21 Python
PyTorch的深度学习入门之PyTorch安装和配置
2019/06/27 Python
python并发爬虫实用工具tomorrow实用解析
2019/09/25 Python
numpy ndarray 取出满足特定条件的某些行实例
2019/12/05 Python
python 负数取模运算实例
2020/06/03 Python
苹果Mac升级:MacSales.com
2017/11/20 全球购物
可口可乐唇膏:Lip Smackers
2019/08/27 全球购物
Java提供了哪些企业应用编程接口
2015/02/13 面试题
C#笔试题和英文面试题
2013/02/07 面试题
中餐厅主管的职责范文
2014/02/04 职场文书
2016年春节慰问信息
2015/03/25 职场文书
2015年百日安全活动总结
2015/03/26 职场文书
银行中层干部培训心得体会
2016/01/11 职场文书
2016党风廉政建设心得体会范文
2016/01/25 职场文书