Beautiful Soup库
安装
- win+X 命令提示符（使用管理员权限启动控制台）
- 输入安装命令
pip install beautifulsoup4
Beautiful Soup库的安装小测
演示HTML页面地址：http://python123.io/ws/demo.html
demo = r.text
from bs4 import BeautifulSoup
soup = BeautifulSoup(demo, "html.parser")
print(soup.prettify())
BeautifulSoup库的基本元素
Beaufitul Soup库的引用
Beautiful Soup库，也叫beautifulsoup4或bs4
from bs4 import BeautifulSoup
from bs4 import BeautifulSoup
soup = BeautifulSoup("<html>data</html>","html.parser")
soup2 = BeautifulSoup(open("D://demo.html"), "html.parser")
BeautifulSoup对应一个HTML/XML文档的全部内容
Beautiful Soup库解析器
| 解析器 |
使用方法 |
条件 |
| bs4的HTML解析器 |
BeautifulSoup(mk, 'html.parser') |
安装bs4库 |
| lxml的HTML解析器 |
BeautifulSoup(mk, 'lxml') |
pip install lxml |
| lxml的XML解析器 |
BeautifulSoup(mk, 'xml') |
pip install lxml |
| html5lib的解析器 |
BeautifulSoup(mk, 'html5lib') |
pip install html5lib |
Beautiful Soup类的基本元素
| 基本元素 |
说明 |
| Tag |
标签，最基本的信息组织党员，分别用<>和</>标明开头和结尾 |
| Name |
标签的名字，<p>...</p>的名字是‘p’，格式：<tag>.name |
| Attributes |
标签的属性，字典形式组织，格式：<tag>.attrs |
| NavigableString |
标签内非属性字符串，<>...</>中字符串，格式：<tag>.string |
| Comment |
标签内字符串的注释部分，一种特殊的Comment类型 |
基于bs4库的HTML内容遍历方法
>>> import requests
>>> r = requests.get("http://python123.io/ws/demo.html")
>>> demo = r.text
>>> demo
'<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 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>'
<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 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>
标签树的下行遍历
| 属性 |
说明 |
| .contents |
子节点的列表，将<tag>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 |
for child in soup.body.children:
print(child)
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 |
>>> soup = BeautifulSoup(demo, "html.parser")
>>> for parent in soup.a.parents:
if parent is None:
print(parent)
else:
print(parent.name)
标签树的平行遍历
| 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 |
for sibling in soup.a.next_siblings:
print(sibling)
for sibling in soup.a.previous_siblings:
print(sibling)
基于bs4库的HTML格式输出
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