美味汤Beautifulsoup 实例
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这个东西需要下载，打开cmd 输入指令pip install bs4 就可以下在这个库了。
它用来解析你爬取过来乱糟糟的html或者xml的代码，会自动帮你整理好。具体用法在上面。
BeautifulSoup里面的两个参数，第一个是爬取的html内容，第二个是用来解析的html解析器。
还有其他解析器
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（来自右上角的视频截图，如有侵权，望告知，定整改。）
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<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>
原来爬动的是这么难看的数据，头皮发麻，用bs4之后做成了汤
<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>
变得这么好看，这是下面代码的soup全内容。
import requests
from bs4 import BeautifulSoup
try:
r=requests.get('https://python123.io/ws/demo.html')
demo=r.text
soup = BeautifulSoup(demo,'html.parser')
# 用来返回标题，也就是用左上角的那个东西 <title>This is a python demo page</title>
print(soup.title)
# 用来返回标签名为a的标签，默认返回第一个a标签 <a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a>
print(soup.a)
print(soup.a.string)
# 返回标签a的标签名 a
print(soup.a.name)
# 返回a标签的父标签的标签名 p
print(soup.a.parent.name)
# 返回a标签的爷爷标签的标签名 body
print(soup.a.parent.parent.name)
tag=soup.a
# 返回a标签的各种属性 {'href': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
print(tag.attrs)
# 返回a标签的class属性的内容 ['py1']
print(tag.attrs['class'])
# 返回a标签的href属性的内容 http://www.icourse163.org/course/BIT-268001
print(tag.attrs['href'])
# 返回类型 <class 'dict'>
print(type(tag.attrs))
# 返回soup.a的数据类型 <class 'bs4.element.Tag'>
print(type(tag))
# 可以穿透内置标签，直接输出string部分的内容 Basic Python
print(tag.string)
tag2=soup.p.string
#The demo python introduces several python courses.
print(tag2.string)
#<class 'bs4.element.NavigableString'>
print(type(tag2.string))
newsoup=BeautifulSoup("<b><!--This is a comment --></b><p>This is not a comment</p>","html.parser")
#This is a comment
print(newsoup.b.string)
#<class 'bs4.element.Comment'>(注释类型）
print(type(newsoup.b.string))
except:
print('爬取失败')
注释都是我自己写的，好好看，还看不懂就重新来过吧，反正没有反正。上面用到较少，了解即可。