w2 Advanced HTML Parsing( including Regexpression )

本文链接：https://blog.youkuaiyun.com/Linli522362242/article/details/90139705

本文详细介绍了使用Python的BeautifulSoup库进行网页数据抓取的方法，包括解析HTML文档、查找特定元素、提取图片链接及处理复杂属性等高级技巧，是网络爬虫开发者的实用指南。

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################################################################

from urllib.request import urlopen
from bs4 import BeautifulSoup

html=urlopen('http://www.pythonscraping.com/pages/page3.html')
bs=BeautifulSoup(html, 'html.parser')

#find_all(tag, attributes, recursive, text, limit, keywords)

nameList = bs.findAll('span', {'class':'green'})

for name in nameList:

print(name.get_text())

nameList = bs.find_all(text='the prince')########
print(len(nameList))

for child in bs.find('table', {'id':'giftList'}).children:
print(child)

for sibling in bs.find('table', {'id':'giftList'}).tr.next_siblings:
    print(sibling)

                     #<img src="../img/gifts/img1.jpg">
print(bs.find('img', {'src':'../img/gifts/img1.jpg'}
             ).parent.previous_sibling.get_text()
            )#   $15.00

#<td>$15.00</td>
#<td><img src="../img/gifts/img1.jpg"></td></tr>

images = bs.find_all('img', {'src':re.compile('\.\.\/img\/gifts\/img.*\.jpg')})
#images = bs.find_all('img', {'src':re.compile('\.\.\/img\/gifts/img.*\.jpg')})

for image in images:
    print(image['src'])

# the following retrieves all tags that have exactly two attributes:

print(
        bs.find_all(lambda tag: len(tag.attrs)==2)
)

That is,
it will find tags with two attributes, such as the following:
<div class="body" id="content"></div>
<span style="color:red" class="title"></span>

################################################################

bs.find_all(lambda tag: tag.get_text() ==
'Or maybe he\'s only resting?')

This can also be accomplished without a lambda function:
bs.find_all('', text='Or maybe he\'s only resting?')

################################################################

from urllib.request import urlopen
from bs4 import BeautifulSoup

html = urlopen('http://www.pythonscraping.com/pages/warandpeace.html')
bs = BeautifulSoup(html.read(), 'html.parser')

#find_all(tag, attributes, recursive, text, limit, keywords)
nameList = bs.findAll('span', {'class':'green'})
for name in nameList:
    print(name.get_text())

nameList = bs.find_all(text='the prince') ############
print(len(nameList))

Result:

http://www.pythonscraping.com/pages/warandpeace.html

...

################################################################

from urllib.request import urlopen
from bs4 import BeautifulSoup

html=urlopen('http://www.pythonscraping.com/pages/page3.html')
bs=BeautifulSoup(html, 'html.parser')
                                                #.descendants
for child in bs.find('table', {'id':'giftList'}).children:
    print(child)

Result:

from urllib.request import urlopen
from bs4 import BeautifulSoup

html = urlopen('http://www.pythonscraping.com/pages/page3.html')
bs = BeautifulSoup(html, 'html.parser')

for sibling in bs.find('table', {'id':'giftList'}).tr.next_siblings:
    print(sibling)

Result:

from urllib.request import urlopen
from bs4 import BeautifulSoup

html = urlopen('http://www.pythonscraping.com/pages/page3.html')
bs = BeautifulSoup(html, 'html.parser')

                     #<img src="../img/gifts/img1.jpg">
print(bs.find('img', {'src':'../img/gifts/img1.jpg'}
             ).parent.previous_sibling.get_text()
            )#   $15.00

#<td>$15.00</td>
#<td><img src="../img/gifts/img1.jpg"></td></tr>

from urllib.request import urlopen
from bs4 import BeautifulSoup
import re

html = urlopen('http://www.pythonscraping.com/pages/page3.html')
bs = BeautifulSoup(html, 'html.parser')

images = bs.find_all('img', {'src':re.compile('\.\.\/img\/gifts\/img.*\.jpg')})

for image in images:
    print(image['src'])

print(
        #bs.find_all(lambda tag: len(tag.attrs)==2)
        bs.find_all(lambda tag: tag.get_text() == 'Or maybe he\'s only resting?')
)