pythonbeautifulsoup库⼊门安装教程
⽬录
beautiful soup库的安装
beautiful soup库的理解
beautiful soup库的引⽤
BeautifulSoup类
回顾demo.html
Tag标签
Tag的attrs（属性）
Tag的NavigableString
HTML基本格式
标签树的下⾏遍历
标签树的上⾏遍历
标签的平⾏遍历
bs库的prettify()⽅法
bs4库的编码
beautiful soup库的安装
pip install beautifulsoup4
beautiful soup库的理解
beautiful soup库是解析、遍历、维护“标签树”的功能库
beautiful soup库的引⽤
from bs4 import BeautifulSoup
import bs4
BeautifulSoup类
BeautifulSoup对应⼀个HTML/XML⽂档的全部内容
回顾demo.html
import requests
r = ("python123.io/ws/demo.html")
demo = r.text
print(demo)
<html><head><title>This is a python demo page</title></head>
<body>
<p class="title"><b>The demo python introduces several python courses.</b></p>
<p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a href="/course/BIT-268001" class="py1" id="link1">Basic Python</a> and <a href="/course/BIT-1001870001" class="py2" id="link2">Advanced Python</a>.</p> </body></html>
Tag标签
基本元素说明
Tag标签，最基本的信息组织单元，分别⽤<>和</>标明开头和结尾
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
java invoke用法demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.title)
tag = soup.a
print(tag)
<title>This is a python demo page</title>
<a href="/course/BIT-268001" >Basic Python</a>
任何存在于HTML语法中的标签都可以⽤soup.访问获得。当HTML⽂档中存在多个相同对应内容时，soup.返回第⼀个
Tag的name
基本元素说明
Name 标签的名字，
…
的名字是'p'，格式：.name
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html") demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.a.name)
print(soup.a.parent.name)
print(soup.a.parent.parent.name)
a
p
body
Tag的attrs（属性）
基本元素说明
Attributes标签的属性，字典形式组织，格式：.attrs
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
tag = soup.a
print(tag.attrs)
print(tag.attrs['class'])
print(tag.attrs['href'])
print(type(tag.attrs))
print(type(tag))
{'href': '/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
['py1']
/course/BIT-268001
<class 'dict'>
<class 'bs4.element.Tag'>
Tag的NavigableString
Tag的NavigableString
基本元素说明
NavigableString标签内⾮属性字符串，<>…</>中字符串，格式：.string
Tag的Comment
基本元素说明
Comment标签内字符串的注释部分，⼀种特殊的Comment类型
import requests
from bs4 import BeautifulSoup
newsoup = BeautifulSoup("<b><!--This is a comment--></b><p>This is not a comment</p>","html.parser")
print(newsoup.b.string)
print(type(newsoup.b.string))
print(newsoup.p.string)
print(type(newsoup.p.string))
This is a comment
<class 'bs4.element.Comment'>
This is not a comment
<class 'bs4.element.NavigableString'>
HTML基本格式
标签树的下⾏遍历
属性说明
.contents⼦节点的列表，将所有⼉⼦结点存⼊列表
.children⼦节点的迭代类型，与.contents类似，⽤于循环遍历⼉⼦结点
.descendents⼦孙节点的迭代类型，包含所有⼦孙节点，⽤于循环遍历
论坛开源模板BeautifulSoup类型是标签树的根节点
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.head)
print(ts)
print(ts)
print(len(ts))
print(ts[1])
springboot控制器注解<head><title>This is a python demo page</title></head>
[<title>This is a python demo page</title>]
['\n', <p ><b>The demo python introduces several python courses.</b></p>, '\n', <p >Python
is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the
following courses:
<a href="/course/BIT-268001" >Basic Python</a> and <a href="/course/BIT-1001870001" >Advanced Python</a>.</p>, '\n'] 5
<p ><b>The demo python introduces several python courses.</b></p>
for child in soup.body.children:
print(child) #遍历⼉⼦结点
for child in soup.body.descendants:
print(child) #遍历⼦孙节点
标签树的上⾏遍历
属性说明
.parent节点的⽗亲标签
.parents节点先辈标签的迭代类型，⽤于循环遍历先辈节点
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.title.parent)
print(soup.html.parent)
<head><title>This is a python demo page</title></head>
<html><head><title>This is a python demo page</title></head>
<body>
<p ><b>The demo python introduces several python courses.</b></p>
正则表达式 中文字符<p >Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a href="/course/BIT-268001" >Basic Python</a> and <a href="/course/BIT-1001870001" >Advanced Python</a>.</p>
</body></html>
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
for parent in soup.a.parents:
if parent is None:
print(parent)
else:
print(parent.name)
p
body
html
[document]
标签的平⾏遍历
属性说明
.next_sibling返回按照HTML⽂本顺序的下⼀个平⾏节点标签
.previous.sibling返回按照HTML⽂本顺序的上⼀个平⾏节点标签
.next_siblings迭代类型，返回按照HTML⽂本顺序的后续所有平⾏节点标签
.previous.siblings迭代类型，返回按照HTML⽂本顺序的前续所有平⾏节点标签
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(_sibling)
print(__sibling)
print(soup.a.previous_sibling)
print(soup.a.previous_sibling.previous_sibling)
print(soup.a.parent)
and
<a class="py2" href="/course/BIT-1001870001" id="link2">Advanced Python</a>
Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
None
<p class="course">Python is a wonderful general-purpose programming language. You can learn Pyt
hon from novice to professional by tracking the following courses:
<a class="py1" href="/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="/course/BIT-1001870001" id="link2">Advanced Python</a>.</p> for sibling in _sibling:
print(sibling) #遍历后续节点
for sibling in soup.a.previous_sibling:
print(sibling) #遍历前续节点
bs库的prettify()⽅法
import requests
from bs4 import BeautifulSoup
r = ("python123.io/ws/demo.html")
数据库的建立代码demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.prettify())
<html>
<head>
<title>
This is a python demo page
</title>
</head>
<body>
<p class="title">
<b>
The demo python introduces several python courses.
</b>
</p>
<p class="course">
Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
Basic Python
</a>
and
<a class="py2" href="/course/BIT-1001870001" id="link2">
Advanced Python
</a>
.
</p>python入门教程(非常详细)书
</body>
</html>
.prettify()为HTML⽂本<>及其内容增加更加'\n'
.prettify()可⽤于标签，⽅法：.prettify()
bs4库的编码
bs4库将任何HTML输⼊都变成utf-8编码
python 3.x默认⽀持编码是utf-8，解析⽆障碍
import requests
from bs4 import BeautifulSoup
soup = BeautifulSoup("<p>中⽂</p>","html.parser")
print(soup.p.string)
print(soup.p.prettify())
中⽂
<p>
中⽂
</p>
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