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🌟Beautiful Soup库入门

(1) 🍉标签基本元素

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
Name	标签的名字， …… 的名字是‘p’，格式：.name
Attributes	标签的属性，字典形式组织，格式：.attrs
NavigableString	标签内非属性字符串，<>……</>中字符串，格式：.string
Comment	标签内字符串的注释部分，一种特殊的Comment类型

1. 最基本的信息单元

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   try:response=requests.get(url)response.raise_for_status()html=response.textsoup=BeautifulSoup(html,"html.parser")title=soup.titlea=soup.aprint(title,a)
   except:print("爬取失败")
   

2. 标签的名字

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   try:response=requests.get(url)response.raise_for_status()html=response.textsoup=BeautifulSoup(html,"html.parser")title=soup.title.name # 获取标签的尖括号里面的内容print(title)
   except:print("爬取失败")
   

3. 标签属性

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   try:response=requests.get(url)response.raise_for_status()html=response.textsoup=BeautifulSoup(html,"html.parser")a=soup.aid=a.attrs # 查看a标签里的属性id_class=a.attrs['href'] # 获取属性的键值对，就是属性内容print(id_class)
   except:print("爬取失败")
   

4. 标签内非属性字符串

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   try:response=requests.get(url)response.raise_for_status()html=response.textsoup=BeautifulSoup(html,"html.parser")p=soup.p.stringprint(p)
   except:print("爬取失败")
   

5. 标签内字符串的注释部分

   from bs4 import BeautifulSoupsoup=BeautifulSoup("<b><!--This is a comment--></b><p>This is not a comment</p>","html.parser")print(type(soup.b.string))
   except:print("爬取失败")
   

(2) 🍉标签树下的下行遍历

属性	说明
.contents	子节点的列表，将所有儿子节点存入列表
.children	子节点的迭代类型，与.contents类似，用于循环遍历儿子节点
.descendants	子孙节点的迭代类型，包含所有子孙节点，用于循环遍历

1. 遍历下行

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   response=requests.get(url)
   soup=BeautifulSoup(response.text,"html.parser")
   head=soup.head.contents
   body=soup.body.contents
   print(head)
   print(body)
   

2. 遍历下行

   import requests
   from bs4 import BeautifulSoup
   url="http://python123.io/ws/demo.html"
   response=requests.get(url)
   soup=BeautifulSoup(response.text,"html.parser")
   # 遍历儿子节点
   for child in soup.body.children:print(child)
   # 遍历子孙节点
   for child in soup.body.descendants:print(child)
   

(3) 🍉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，用于循环遍历辈点

import requests
from bs4 import BeautifulSoup
url="http://python123.io/ws/demo.html"
response=requests.get(url)
soup=BeautifulSoup(response.text,"html.parser")
title=soup.title.parent
print(title)
for parent in soup.a.parents:if parent is None:print(parent)else:print(parent.name)

(4) 🍉标签树的平衡遍历

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
url="http://python123.io/ws/demo.html"
response=requests.get(url)
soup=BeautifulSoup(response.text,"html.parser")
a0=soup.a.next_sibling
print(a0)
a1=soup.a.next_sibling.next_sibling
print(a1)
a2=soup.a.previous_sibling
print(a2)
a3=soup.a.previous_sibling.previous_sibling
print(a3)
a4=soup.a.parent
print(a4)
# 遍历后续节点
for sibling in soup.a.next_sibling:print(sibling)
# 遍历前续节点
for sibling in soup.a.previous_sibling:print(sibling)

• .prettify()为HTML文本<>及其内容增加更加”\n“

• .prettofuy()可用与标签，方法：.prettift()

import requests
from bs4 import BeautifulSoup
url="http://python123.io/ws/demo.html"
response=requests.get(url)
soup=BeautifulSoup(response.text,"html.parser")
print(soup.prettify())