bs4模块使用（二）

遍历文档树

怎样从文档的一段内容找到另一段内容?

html_doc = """
<html><head><title>The Dormouse's story</title></head><body>
<p class="title"><b>The Dormouse's story</b></p><p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p><p class="story">...</p>
"""from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, 'html.parser')

子节点

一个Tag可能包含多个字符串或其它的Tag,这些都是这个Tag的子节点

tag名字

想要获取节点，最简单的方法就是提供tag名字，甚至可以在文档树的tag中多次调用这个方法

通过点取属性的方式只能获得当前名字的第一个tag，后面会介绍获取全部

print(soup.head)
print(soup.title)
print(soup.body.p)

.contents和.children

.contents
.contents 属性可以将tag的子节点以列表的方式输出
.children
通过tag的 .children 生成器,可以对tag的子节点进行循环


print(soup.body.contents)for item in soup.body.children:print(item)

字符串没有子节点
.contents和.children属性获取的子节点，仅包含tag的直接子节点

.descendants

.descendants属性，不仅可以获取直接子节点，子孙节点也可以获取

html_doc = """<html><head><title>The Dormouse's story</title></head><body><p class="title"><b>The Dormouse's story</b></p><p class="story">Once upon a time there were three little sisters; and their names were<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;and they lived at the bottom of a well.</p><p class="story">...</p>"""soup = BeautifulSoup(html_doc,features="lxml")for item in soup.body.descendants:print(item)print("--------------")
for item in soup.body.contents:print(item)
print("--------------")for item in soup.body.children:print(item)