• Beautiful Soup库是解析、遍历、维护“标签树”的功能库
• BeautifulSoup对应一个HTML/XML文档的全部内容
• Beautiful Soup库也叫beautifulsoup4 或 bs4 约定引用方式如下，即主要是用BeautifulSoup类

from bs4 import BeautifulSoup
import bs4

安装

pip install beautifulsoup4

解析器

基本元素

使用方法

import requests
from bs4 import BeautifulSoup

r = requests.get("http://python123.io/ws/demo.html")
demo = r. text
soup = BeautifulSoup(demo, 'html.parser')

tag

print(soup.title)
print(soup.a)

name

print(soup.a.name)
print(soup.a.parent.name)

attrs(属性)

print(soup.a.attrs)
print(soup.a.attrs['class'])
print(type(soup.a.attrs))

NavigableString

print(soup.p)
print(soup.p.string)
print(type(soup.p.string))

Comment

#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))

HTML的内容遍历

HTML基本格式@2x.png

HTML树形结构@2x.png

遍历图解@2x.png

下行遍历

print(soup.head)
print(soup.head.contents)
print(soup.body.contents)
print(len(soup.body.contents))
print(soup.body.contents[1])

# 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)

上行遍历

 print(soup.title.parent)

 for parent in soup.a.parents:
    if parent is None:
        print(parent)
    else:
        print(parent.name)

平行遍历

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)


# 遍历后续节点
for sibling in soup.a.next_siblings:
    print(sibling)

# 遍历前续节点
for sibling in soup.a.previous_siblings:
    print(sibling)

格式输出

bs4库的prettify()方法:

• .prettify()为HTML文本<>及其内容增加更加'\n'
• .prettify()可用于标签，方法:<tag>.prettify()

print(soup.prettify())
print(soup.a.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