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
学习python处理python编码问题
Mar 13 Python
win系统下为Python3.5安装flask-mongoengine 库
Dec 20 Python
Python爬虫实例_城市公交网络站点数据的爬取方法
Jan 10 Python
python实现Adapter模式实例代码
Feb 09 Python
对命令行模式与python交互模式介绍
May 12 Python
对numpy中向量式三目运算符详解
Oct 31 Python
python实现维吉尼亚算法
Mar 20 Python
Python网络编程之使用TCP方式传输文件操作示例
Nov 01 Python
Python内置方法和属性应用:反射和单例(推荐)
Jun 19 Python
基于python实现ROC曲线绘制广场解析
Jun 28 Python
如何用python开发Zeroc Ice应用
Jan 29 Python
教你漂亮打印Pandas DataFrames和Series
May 29 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
PHP中的switch语句的用法实例详解
2015/10/21 PHP
用JAVASCRIPT如何给&amp;lt;textarea&amp;gt;&amp;lt;/textarea&amp;gt;赋值
2007/04/20 Javascript
jQuery语法总结和注意事项小结
2012/11/11 Javascript
jQuery插件Slider Revolution实现响应动画滑动图片切换效果
2015/06/05 Javascript
JQuery实现的图文自动轮播效果插件
2015/06/19 Javascript
javascript基于prototype实现类似OOP继承的方法
2015/12/16 Javascript
AngularJS中实现显示或隐藏动画效果的方式总结
2015/12/31 Javascript
javascript合并表格单元格实例代码
2016/01/03 Javascript
js获取鼠标点击的对象,点击另一个按钮删除该对象的实现代码
2016/05/13 Javascript
JS实现京东首页之页面顶部、Logo和搜索框功能
2017/01/12 Javascript
js仿搜狐视频记录片列表展示效果
2020/05/30 Javascript
jQuery实现级联下拉框实战(5)
2017/02/08 Javascript
React中上传图片到七牛的示例代码
2017/10/10 Javascript
vue.js 实现点击展开收起动画效果
2018/07/07 Javascript
vue组件开发之用户无限添加自定义填写表单的方法
2018/08/28 Javascript
jQuery高级编程之js对象、json与ajax用法实例分析
2019/11/01 jQuery
JS错误处理与调试操作实例分析
2020/04/13 Javascript
vue实现员工信息录入功能
2020/06/11 Javascript
详解vue-router的导航钩子(导航守卫)
2020/11/02 Javascript
[05:24]TI9采访——教练
2019/08/24 DOTA
Python实现统计单词出现的个数
2015/05/28 Python
Python 多线程Threading初学教程
2017/08/22 Python
Python3 循环语句(for、while、break、range等)
2017/11/20 Python
Python的numpy库中将矩阵转换为列表等函数的方法
2018/04/04 Python
python Tkinter版学生管理系统
2019/02/20 Python
Python 调用 Windows API COM 新法
2019/08/22 Python
Python matplotlib绘制饼状图功能示例
2019/09/10 Python
Python的形参和实参使用方式
2019/12/24 Python
Python continue语句实例用法
2020/02/06 Python
英国领先的男士服装和时尚零售商:Burton
2017/01/09 全球购物
BIFFI美国站:意大利BIFFI BOUTIQUES豪华多品牌时装零售公司
2020/02/11 全球购物
JSP&Servlet技术面试题
2015/05/21 面试题
化工专业应届生求职信
2013/11/08 职场文书
雪山饭庄的创业计划书范文
2014/01/18 职场文书
办公室文员工作职责
2014/01/31 职场文书
安全生产管理责任书
2014/04/16 职场文书