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 = requests.get("http://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">The demo python introduces several python courses.</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="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> </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 = requests.get("http://python123.io/ws/demo.html")
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="http://www.icourse163.org/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 = requests.get("http://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 = requests.get("http://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': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
['py1']
http://www.icourse163.org/course/BIT-268001
<class 'dict'>
<class 'bs4.element.Tag'>
Tag的NavigableString
Tag的NavigableString
| 基本元素 | 说明 |
|---|---|
| NavigableString | http://www.cppcns.com标签内非属性字符串，<>…</>中字符串，格式：.string |
| 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("<!--This is a comment--><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 |
BeautifulSoup类型是标签树的根节点
import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.head)
print(soup.head.contents)
print(soup.body.contents)
print(len(soup.body.contents))
print(soup.body.contents[1])
<head><title>This is a python demo page</title></head> [<title>This is a python demo page</title>] ['\n', <p >The demo python introduces several python courses.</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="http://www.icourse163.org/course/BIT-268001" >Basic Python</a> and <a href="http://www.icourse163.org/course/BIT-1001870001" >Advanced Python</a>.</p>, '\n'] 5 <p >The demo python introduces several python courses.</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 = requests.get("http://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 >The demo python introduces several pythttp://www.cppcns.comhon courses.</p> <p >Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses: <a href="http://www.icourse163.org/course/BIT-268001" >Basic Python</a> and <a href="http://www.icourse163.org/course/BIT-1001870001" >Advanced Python</a>.</p> </body></html>
import requests
from bs4 import BeautifulSoup
r = requests.get("http://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 = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.a.next_sibling)
print(soup.a.next_sibling.next_sibling)
print(soup.a.previous_sibling)
print(soup.a.previous_sibling.previous_sibling)
print(soup.a.parent)
and <a class="py2" href="http://www.icourse163.org/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 lhttp://www.cppcns.comearn 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>
for sibling in soup.a.next_sibling: print(sibling) #遍历后续节点 for sibling in soup.a.previous_sibling: print(sibling) #遍历前续节点
bs库的prettify()方法
import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.prettify())
编程客栈<html>
<head>
<title>
This is a python demo page
</title>
</head编程客栈>
<body>
<p class="title">
The demo python introduces several python courses.
</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="http://www.icourse163.org/course/BIT-1001870001" id="link2">
Advanced Python
</a>
.
</p>
</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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