14 基于bs4库的HTML内容遍历方法

<html><head><title>This is a python demo page</title></head>

<body>

The demo python introduces several python courses.

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>.

</body></html>

方法一：下行遍历

"""12 基于bs4库的HTML内容遍历方法"""


import requests
from bs4 import BeautifulSoup

#方法一：下行遍历
url = "https://python123.io/ws/demo.html"
r = requests.get(url)
demo = r.text
soup = BeautifulSoup(demo, "html.parser")
# <head><title>This is a python demo page</title></head>
print(soup.head)
# [<title>This is a python demo page</title>]
print(soup.head.contents)

print(soup.body.contents)
# 5
print(len(soup.body.contents))      # 注意回车也是其元素
print(soup.body.contents[1])
# 使用.contents输出其元素
print('*'*10)
for content in soup.body.contents:
    print(content)
    print('*'*10)
    

###############################
print('#'*10)
# 使用.chidlren输出
for child in soup.body.children:
    print(child)
    print('#' * 10)

print('$'*10)
# 使用.descendants输出
for descendant in soup.body.descendants:
    print(descendant)
    print('$' * 10)

方法二：上行遍历

"""12 基于bs4库的HTML内容遍历方法"""


import requests
from bs4 import BeautifulSoup


#方法二：上行遍历
url = "https://python123.io/ws/demo.html"
r = requests.get(url)
demo = r.text
soup = BeautifulSoup(demo, "html.parser")
# <head><title>This is a python demo page</title></head>
print(soup.title.parent)

print(soup.head.parent)     # 整个html
print('$' * 30)
print(soup.html.parent)     # 整个html
print('$' * 30)
print(soup.parent)      # None

###############
"""
p
body
html
[document]
"""
for parent in soup.a.parents:
    if parent is None:
        print(parent)
    else:
        print(parent.name)

方法三：平行遍历

"""12 基于bs4库的HTML内容遍历方法"""


import requests
from bs4 import BeautifulSoup


#方法三：平行遍历
url = "https://python123.io/ws/demo.html"
r = requests.get(url)
demo = r.text
soup = BeautifulSoup(demo, "html.parser")
#  and
print(soup.a.next_sibling)

print(soup.a.next_sibling.next_sibling)

print(soup.a.previous_sibling)
# None
print(soup.a.previous_sibling.previous_sibling)

#对a标签后序结点进行遍历
print('#'*30)
for sibling in soup.a.next_siblings:
    print(sibling)
    print('#'*30)

#对a标签前序结点进行遍历
print('@'*30)
for sibling in soup.a.previous_siblings:
    print(sibling)
    print('@'*30)