html_doc = '''
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="sister"><b>$37</b></p>
<p class="story" id="p">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" >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,'lxml')
print(soup)
print(type(soup))
# 遍历文档树
# *****1、直接使用
print(soup.html)
print(type(soup.html))
print(soup.a)
print(soup.p)
# *****2、获取标签的名称
print(soup.a.name)
# *****3、获取标签的属性
print(soup.a.attrs)
# 获取a标签中所有属性
print(soup.a.attrs['href'])
# ***** 4、获取标签的文本内容
print(soup.p.text)
# 5、嵌套选择
print(soup.html.body.p)
# 6、子节点、子孙节点
print(soup.p.children)
# 返回迭代器对象
print(list(soup.p.children))
# 7、父节点、祖先节点
print(soup.b.parent)
print(soup.b.parents)
print(list(soup.b.parents))
# 8、兄弟节点(sibling:兄弟姐妹)
print(soup.a)
# 获取下一个兄弟节点
print(soup.a.next_sibling)
# 获取下一个的所有兄弟节点,返回的是一个生成器
print(soup.a.next_siblings)
print(list(soup.a.next_siblings))
# 获取上一个兄弟节点
print(soup.a.previous_sibling)
# 获取上一个的所有兄弟节点，返回的是一个生成器
print(list(soup.a.previous_siblings))