前言
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前言
在信息爆炸的时代，互联网上的海量文字信息如同无尽的沙滩。然而，其中真正有价值的信息往往埋在各种网页中，需要经过筛选和整理才能被有效利用。幸运的是，Python这个强大的编程语言可以帮助我们完成这项任务。
本文将介绍如何使用Python将网页文字转换为Markdown格式，这将使得我们能够更加方便地阅读和处理网页内容。无论是将文章保存为本地文件还是转化为其他格式，Markdown都能够提供清晰简洁的排版和格式，让我们更加专注于内容本身。
正则表达式
我们将页面进行Maekdown的转换为了保证准确度，我们可以使用正则表达式去修改，如下
import re
__all__ = ['Tomd', 'convert']
MARKDOWN = {
'h1': ('\n# ', '\n'),
'h2': ('\n## ', '\n'),
'h3': ('\n### ', '\n'),
'h4': ('\n#### ', '\n'),
'h5': ('\n##### ', '\n'),
'h6': ('\n###### ', '\n'),
'code': ('`', '`'),
'ul': ('', ''),
'ol': ('', ''),
'li': ('- ', ''),
'blockquote': ('\n> ', '\n'),
'em': ('**', '**'),
'strong': ('**', '**'),
'block_code': ('\n```\n', '\n```\n'),
'span': ('', ''),
'p': ('\n', '\n'),
'p_with_out_class': ('\n', '\n'),
'inline_p': ('', ''),
'inline_p_with_out_class': ('', ''),
'b': ('**', '**'),
'i': ('*', '*'),
'del': ('~~', '~~'),
'hr': ('\n---', '\n\n'),
'thead': ('\n', '|------\n'),
'tbody': ('\n', '\n'),
'td': ('|', ''),
'th': ('|', ''),
'tr': ('', '\n')
}
BlOCK_ELEMENTS = {
'h1': '<h1.*?>(.*?)</h1>',
'h2': '<h2.*?>(.*?)</h2>',
'h3': '<h3.*?>(.*?)</h3>',
'h4': '<h4.*?>(.*?)</h4>',
'h5': '<h5.*?>(.*?)</h5>',
'h6': '<h6.*?>(.*?)</h6>',
'hr': '<hr/>',
'blockquote': '<blockquote.*?>(.*?)</blockquote>',
'ul': '<ul.*?>(.*?)</ul>',
'ol': '<ol.*?>(.*?)</ol>',
'block_code': '<pre.*?><code.*?>(.*?)</code></pre>',
'p': '<p\s.*?>(.*?)</p>',
'p_with_out_class': '<p>(.*?)</p>',
'thead': '<thead.*?>(.*?)</thead>',
'tr': '<tr>(.*?)</tr>'
}
INLINE_ELEMENTS = {
'td': '<td>(.*?)</td>',
'tr': '<tr>(.*?)</tr>',
'th': '<th>(.*?)</th>',
'b': '<b>(.*?)</b>',
'i': '<i>(.*?)</i>',
'del': '<del>(.*?)</del>',
'inline_p': '<p\s.*?>(.*?)</p>',
'inline_p_with_out_class': '<p>(.*?)</p>',
'code': '<code.*?>(.*?)</code>',
'span': '<span.*?>(.*?)</span>',
'ul': '<ul.*?>(.*?)</ul>',
'ol': '<ol.*?>(.*?)</ol>',
'li': '<li.*?>(.*?)</li>',
'img': '<img.*?src="(.*?)".*?>(.*?)</img>',
'a': '<a.*?href="(.*?)".*?>(.*?)</a>',
'em': '<em.*?>(.*?)</em>',
'strong': '<strong.*?>(.*?)</strong>'
}
DELETE_ELEMENTS = ['<span.*?>', '</span>', '<div.*?>', '</div>']
class Element:
def __init__(self, start_pos, end_pos, content, tag, is_block=False):
self.start_pos = start_pos
self.end_pos = end_pos
self.content = content
self._elements = []
self.is_block = is_block
self.tag = tag
self._result = None
if self.is_block:
self.parse_inline()
def __str__(self):
wrapper = MARKDOWN.get(self.tag)
self._result = '{}{}{}'.format(wrapper[0], self.content, wrapper[1])
return self._result
def parse_inline(self):
for tag, pattern in INLINE_ELEMENTS.items():
if tag == 'a':
self.content = re.sub(pattern, '[\g<2>](\g<1>)', self.content)
elif tag == 'img':
self.content = re.sub(pattern, '', self.content)
elif self.tag == 'ul' and tag == 'li':
self.content = re.sub(pattern, '- \g<1>', self.content)
elif self.tag == 'ol' and tag == 'li':
self.content = re.sub(pattern, '1. \g<1>', self.content)
elif self.tag == 'thead' and tag == 'tr':
self.content = re.sub(pattern, '\g<1>\n', self.content.replace('\n', ''))
elif self.tag == 'tr' and tag == 'th':
self.content = re.sub(pattern, '|\g<1>', self.content.replace('\n', ''))
elif self.tag == 'tr' and tag == 'td':
self.content = re.sub(pattern, '|\g<1>', self.content.replace('\n', ''))
else:
wrapper = MARKDOWN.get(tag)
self.content = re.sub(pattern, '{}\g<1>{}'.format(wrapper[0], wrapper[1]), self.content)
class Tomd:
def __init__(self, html='', options=None):
self.html = html
self.options = options
self._markdown = ''
def convert(self, html, options=None):
elements = []
for tag, pattern in BlOCK_ELEMENTS.items():
for m in re.finditer(pattern, html, re.I | re.S | re.M):
element = Element(start_pos=m.start(),
end_pos=m.end(),
content=''.join(m.groups()),
tag=tag,
is_block=True)
can_append = True
for e in elements:
if e.start_pos < m.start() and e.end_pos > m.end():
can_append = False
elif e.start_pos > m.start() and e.end_pos < m.end():
elements.remove(e)
if can_append:
elements.append(element)
elements.sort(key=lambda element: element.start_pos)
self._markdown = ''.join([str(e) for e in elements])
for index, element in enumerate(DELETE_ELEMENTS):
self._markdown = re.sub(element, '', self._markdown)
return self._markdown
@property
def markdown(self):
self.convert(self.html, self.options)
return self._markdown
_inst = Tomd()
convert = _inst.convert
这段代码是一个用于将HTML转换为Markdown的工具类。它使用了正则表达式来解析HTML标签，并根据预定义的转换规则将其转换为对应的Markdown格式。
代码中定义了一个Element类，用于表示HTML中的各个元素。Element类包含了标签的起始位置、结束位置、内容、标签类型等信息。它还提供了一个parse_inline方法，用于解析内联元素，并将其转换为Markdown格式。
Tomd类是主要的转换类，它接受HTML字符串并提供了convert方法来执行转换操作。convert方法遍历预定义的HTML标签模式，并使用正则表达式匹配HTML字符串中对应的部分。然后创建相应的Element对象并进行转换操作。最后，将转换后的Markdown字符串返回。
在模块顶部，MARKDOWN字典定义了各个HTML标签对应的Markdown格式。BlOCK_ELEMENTS和INLINE_ELEMENTS字典定义了正则表达式模式，用于匹配HTML字符串中的块级元素和内联元素。DELETE_ELEMENTS列表定义了需要删除的HTML元素。
那么既然有了转markdown的工具，我们就可以对网页进行转换
进行转换
首先，
result_file函数用于创建一个保存结果文件的路径。它接受文件夹的用户名、文件名和文件夹名作为参数，并在指定的文件夹路径下创建一个新的文件，并返回该文件的路径。
get_headers函数用于从一个文本文件中读取Cookie，并将它们保存为字典形式。它接受包含Cookie的文本文件路径作为参数。
delete_ele函数用于删除BeautifulSoup对象中指定的标签。它接受一个BeautifulSoup对象和待删除的标签列表作为参数，并通过使用该对象的select方法来选择要删除的标签，然后使用decompose方法进行删除。
delete_ele_attr函数用于删除BeautifulSoup对象中指定标签的指定属性。它接受一个BeautifulSoup对象和待删除的属性列表作为参数，并使用find_all方法来选取所有标签，然后使用Python的del语句删除指定的属性。
delete_blank_ele函数用于删除BeautifulSoup对象中的空白标签。它接受一个BeautifulSoup对象和一个例外列表，对于不在例外列表中且内容为空的标签，使用decompose方法进行删除。
TaskQueue类是一个简单的任务队列，用于存储已访问的和未访问的URL。它提供了一系列方法来操作这些列表。
def result_file(folder_username, file_name, folder_name):
folder = os.path.join(os.path.dirname(os.path.realpath(__file__)), "..", folder_name, folder_username)
if not os.path.exists(folder):
try:
os.makedirs(folder)
except Exception:
pass
path = os.path.join(folder, file_name)
file = open(path,"w")
file.close()
else:
path = os.path.join(folder, file_name)
return path
def get_headers(cookie_path:str):
cookies = {}
with open(cookie_path, "r", encoding="utf-8") as f:
cookie_list = f.readlines()
for line in cookie_list:
cookie = line.split(":")
cookies[cookie[0]] = str(cookie[1]).strip()
return cookies
def delete_ele(soup:BeautifulSoup, tags:list):
for ele in tags:
for useless_tag in soup.select(ele):
useless_tag.decompose()
def delete_ele_attr(soup:BeautifulSoup, attrs:list):
for attr in attrs:
for useless_attr in soup.find_all():
del useless_attr[attr]
def delete_blank_ele(soup:BeautifulSoup, eles_except:list):
for useless_attr in soup.find_all():
try:
if useless_attr.name not in eles_except and useless_attr.text == "":
useless_attr.decompose()
except Exception:
pass
class TaskQueue(object):
def __init__(self):
self.VisitedList = []
self.UnVisitedList = []
def getVisitedList(self):
return self.VisitedList
def getUnVisitedList(self):
return self.UnVisitedList
def InsertVisitedList(self, url):
if url not in self.VisitedList:
self.VisitedList.append(url)
def InsertUnVisitedList(self, url):
if url not in self.UnVisitedList:
self.UnVisitedList.append(url)
def RemoveVisitedList(self, url):
self.VisitedList.remove(url)
def PopUnVisitedList(self,index=0):
url = []
if index and self.UnVisitedList:
url = self.UnVisitedList[index]
del self.UnVisitedList[:index]
elif self.UnVisitedList:
url = self.UnVisitedList.pop()
return url
def getUnVisitedListLength(self):
return len(self.UnVisitedList)
class CSDN(object):
def __init__(self, username, folder_name, cookie_path):
# self.headers = {
# "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.70 Safari/537.36"
# }
self.headers = get_headers(cookie_path)
self.s = requests.Session()
self.username = username
self.TaskQueue = TaskQueue()
self.folder_name = folder_name
self.url_num = 1
def start(self):
num = 0
articles = [None]
while len(articles) > 0:
num += 1
url = u'https://blog.csdn.net/' + self.username + '/article/list/' + str(num)
response = self.s.get(url=url, headers=self.headers)
html = response.text
soup = BeautifulSoup(html, "html.parser")
articles = soup.find_all('div', attrs={"class":"article-item-box csdn-tracking-statistics"})
for article in articles:
article_title = article.a.text.strip().replace(' ','：')
article_href = article.a['href']
with ensure_memory(sys.getsizeof(self.TaskQueue.UnVisitedList)):
self.TaskQueue.InsertUnVisitedList([article_title, article_href])
def get_md(self, url):
response = self.s.get(url=url, headers=self.headers)
html = response.text
soup = BeautifulSoup(html, 'lxml')
content = soup.select_one("#content_views")
# 删除注释
for useless_tag in content(text=lambda text: isinstance(text, Comment)):
useless_tag.extract()
# 删除无用标签
tags = ["svg", "ul", ".hljs-button.signin"]
delete_ele(content, tags)
# 删除标签属性
attrs = ["class", "name", "id", "onclick", "style", "data-token", "rel"]
delete_ele_attr(content,attrs)
# 删除空白标签
eles_except = ["img", "br", "hr"]
delete_blank_ele(content, eles_except)
# 转换为markdown
md = Tomd(str(content)).markdown
return md
def write_readme(self):
print("+"*100)
print("[++] 开始爬取 {} 的博文 ......".format(self.username))
print("+"*100)
reademe_path = result_file(self.username,file_name="README.md",folder_name=self.folder_name)
with open(reademe_path,'w', encoding='utf-8') as reademe_file:
readme_head = "# " + self.username + " 的博文\n"
reademe_file.write(readme_head)
for [article_title,article_href] in self.TaskQueue.UnVisitedList[::-1]:
text = str(self.url_num) + '. [' + article_title + ']('+ article_href +')\n'
reademe_file.write(text)
self.url_num += 1
self.url_num = 1
def get_all_articles(self):
try:
while True:
[article_title,article_href] = self.TaskQueue.PopUnVisitedList()
try:
file_name = re.sub(r'[\/:：*?"<>|]','-', article_title) + ".md"
artical_path = result_file(folder_username=self.username, file_name=file_name, folder_name=self.folder_name)
md_head = "# " + article_title + "\n"
md = md_head + self.get_md(article_href)
print("[++++] 正在处理URL：{}".format(article_href))
with open(artical_path, "w", encoding="utf-8") as artical_file:
artical_file.write(md)
except Exception:
print("[----] 处理URL异常：{}".format(article_href))
self.url_num += 1
except Exception:
pass
def muti_spider(self, thread_num):
while self.TaskQueue.getUnVisitedListLength() > 0:
thread_list = []
for i in range(thread_num):
th = threading.Thread(target=self.get_all_articles)
thread_list.append(th)
for th in thread_list:
th.start()
lock = threading.Lock()
total_mem= 1024 * 1024 * 500 #500MB spare memory
@contextlib.contextmanager
def ensure_memory(size):
global total_mem
while 1:
with lock:
if total_mem > size:
total_mem-= size
break
time.sleep(5)
yield
with lock:
total_mem += size
def spider_user(username: str, cookie_path:str, thread_num: int = 10, folder_name: str = "articles"):
if not os.path.exists(folder_name):
os.makedirs(folder_name)
csdn = CSDN(username, folder_name, cookie_path)
csdn.start()
th1 = threading.Thread(target=csdn.write_readme)
th1.start()
th2 = threading.Thread(target=csdn.muti_spider, args=(thread_num,))
th2.start()
def spider(usernames: list, cookie_path:str, thread_num: int = 10, folder_name: str = "articles"):
for username in usernames:
try:
user_thread = threading.Thread(target=spider_user,args=(username, cookie_path, thread_num, folder_name))
user_thread.start()
print("[++] 开启爬取 {} 博文进程成功 ......".format(username))
except Exception:
print("[--] 开启爬取 {} 博文进程出现异常 ......".format(username))
我们可以自定义一个测试类运行一下，在本地文件位置会生成一个文件夹，并将markdown文件输出出来
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