Meta Blogging

Meta Blogging

由来

偶然想到说如果哪一天cnblogs挂了，那之前记录的随笔怎么办？可不可以把它们给download下来本地保存一份。正好看到有个库叫requests, 干嘛不试试看呢。

开工

有了requests 和 beautifulsoup，代码其实很简单。唯一需要注意的是，不能太频繁地用requests.get来抓取网页，不然会报错。一般的网站都会有类似的自我保护机制吧，防止被爬虫给爬死了。

import requests
from BeautifulSoup import BeautifulSoup
import re
import os
import time


URL='http://www.cnblogs.com/fangwenyu/p/'
URL_PATTERN = 'http://www.cnblogs.com/fangwenyu/p|archive'
pattern = re.compile(URL_PATTERN)
DIRECTORY = os.path.dirname(__file__)
ESCAPE_CHARS = '/\:*?"<>|' # Those characters are not allowed to be used in file name in Windows.
tbl = {ord(char): u'' for char in ESCAPE_CHARS}

# get the total page number
page_count = 0
resp = requests.get(URL)
if resp.status_code == requests.codes.ok:
    soup = BeautifulSoup(resp.content)
    attr = {'class':'Pager'}
    result = soup.find('div', attr)
    page_count = int(result.getText()[1:2])

with open(os.path.join(DIRECTORY, 'blog_archive.txt'), 'w') as blog_archive:
    for page in range(1,page_count+1):
        param = {'page':page}
        resp = requests.get(URL, params=param)
        soup = BeautifulSoup(resp.content, convertEntities=BeautifulSoup.HTML_ENTITIES)
        
        blog_list = [(a.getText(), a.get('href')) for a in soup.findAll('a', id=True, href=pattern)]
        for title, link in blog_list:
            norm_title = title.translate(tbl)
            item = '%s |[%s]| %s ' % (title, norm_title, link)
            blog_archive.write(item.encode('utf-8'))
            blog_archive.write('\n')
            
            with open(os.path.join(DIRECTORY, norm_title + '.html'), 'w') as f:
                f.write(requests.get(link).content)
        
        # sleep for some time as access the cnblogs too freqently will cause the server not respond.
        # Something like this -- 
        # ...
        # requests.exceptions.ConnectionError: ('Connection aborted.', error(10060, 'A connection attempt failed 
        # because the connected party did not properly respond after a period of time, or established connection failed 
        # because connected host has failed to respond'))
        time.sleep(5)