Beautiful Soup 库

2023-10-12 17:34:28

理解

基本元素

from bs4 import BeautifulSoup
soup = BeautifulSoup(demo,'html.parser')
r = requests.get("http://python123.io/ws/demo.html")
r.text
'<html><head><title>This is a python demo page</title></head>\r\n<body>\r\n<p class="title"><b>The demo python introduces several python courses.</b></p>\r\n<p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:\r\n<a href="http://www.icourse163.org/course/BIT-268001" class="py1" id="link1">Basic Python</a> and <a href="http://www.icourse163.org/course/BIT-1001870001" class="py2" id="link2">Advanced Python</a>.</p>\r\n</body></html>'
demo = r.text
#bs4的prettify()方法可以使HTML内容更加友好的显示
soup.prettify()  
'<html>\n <head>\n  <title>\n   This is a python demo page\n  </title>\n </head>\n <body>\n  <p class="title">\n   <b>\n    The demo python introduces several python courses.\n   </b>\n  </p>\n  <p class="course">\n   Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:\n   <a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">\n    Basic Python\n   </a>\n   and\n   <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">\n    Advanced Python\n   </a>\n   .\n  </p>\n </body>\n</html>'
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:
   <a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">
    Basic Python
   </a>
   and
   <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">
    Advanced Python
   </a>
   .
  </p>
 </body>
</html>
>>> soup.title
<title>This is a python demo page</title>
#.prettify()为HTML文本<>及其内容增加 '\n'
#.prettify()可用于标签，方法 : <tag>.prettify()
print(soup.a.prettify())
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">
 Basic Python
</a>

>>> soup.title
<title>This is a python demo page</title>
# 任何存在于HTML语法中的标签都可用soup.<tag>访问获得
# 当文档中存在多个相同<tag>对应内容时，soup.<tag>返回第一个
>>> tag = soup.a
>>> tag
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a>
>>> tag = soup.p
>>> tag
<p class="title"><b>The demo python introduces several python courses.</b></p>
>>> tag = soup.a

>>> tag.attrs
{'href': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
#每个<tag>都有自己的名字，通过<tag>.name获取，得到的名字为字符串类型
>>> soup.a.name
'a'
>>> soup.p.name
'p'
>>> soup.a.parent.parent.name
'body'
#一个<tag>可有0个或多个属性，得到的属性表示方式为字典类型
>>> tag.attrs
{'href': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
>>> tag.attrs['class']
['py1']
>>> tag.attrs['href']
'http://www.icourse163.org/course/BIT-268001'
>>> type(tag.attrs)
<class 'dict'>
>>> type(tag)
<class 'bs4.element.Tag'>

#Tag的NavigableString

#Tag的Comment

基于bs4库的HTML内容遍历方法

>>>标签树的下行遍历 BeautifulSoup类型是标签树的根节点

>>> soup = BeautifulSoup(demo,"html.parser")
>>> soup.head
<head><title>This is a python demo page</title></head>
>>> soup.head.contents
[<title>This is a python demo page</title>]
>>> soup.body
<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 track
ing the following courses:

<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icour
se163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>
</body>
#######
>>> soup.body.contents
[[0]'\n',[1] <p class="title"><b>The demo python introduces several python courses.</b></p>, [2]'\n',[3] <p class="course">Python is a won
derful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:

<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icour
se163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>,[4] '\n']
>>> len(soup.body.contents)
5
>>> soup.body.contents[2]
'\n'
###########################################################
for child in soup.body.childern:
    print(child)   #遍历儿子节点
for child in soup.body.descendants:
    print(child)   #遍历子孙节点

>>>标签树的上行遍历

>>> 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]
>>>

>>>标签树的平行遍历

>>> soup
<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 class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>
</body></html>
>>> soup.a.next_sibling
' and '
>>> soup.a.next_sibling.next_sibling
<a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>

#标签树的平行遍历
for sibling in soup.a.next_sibling:
    print(sibling)            #遍历后续节点
for sibling in soup.a.previous_sibling:
    print(sibling)           #遍历后续节点

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