python获取知乎问题答案并转换为MarkDown文件

前期准备

• python2.7
• html2text
• markdownpad(这里随意，只要可以支持md就行)
• 会抓包
• 最重要的是你要有代理，因为知乎开始封IP了

原理

原理说起来很简单：获取请求到的内容的BODY部分，然后重新构建一个HTML文件，接着利用html2text这个模块将其转换为markdown文件，最后对图片及标题按照markdown的格式做一些处理就好了。目前应用的场景主要是在知乎。

代码实现

获取知乎答案

写代码的时候，主要考虑了两种使用场景。第一，获取某一特定答案的数据然后进行转换；第二，获取某一个问题的所有答案进行然后挨个进行转换，在这里可以 通过赞同数来对要获取的答案进行质量控制。

某一个特定答案的数据获取

url：https://www.zhihu.com/question/27621722/answer/48658220
'''
（前面那个是问题ID，后边的是答案ID）
'''
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这一数据的获取我这里分为了两个部分，第一部分请求上述网址，拿到答案主体数据以及赞同数，第二部分请求下面这个接口：

https://www.zhihu.com/api/v4/answers/48658220
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为什么会这样？因为这个接口得到的答案正文数据不是完整数据，所以只能分两步了。

某一个特定答案的数据获取

这一个数据就可以通过很简单的方式得到了，接口如下：

https://www.zhihu.com/api/v4/questions/27621722/answers?sort_by=default&include=data%5B%2A%5D.is_normal%2Cis_collapsed%2Ccollapse_reason%2Cis_sticky%2Ccollapsed_by%2Csuggest_edit%2Ccomment_count%2Ccan_comment%2Ccontent%2Ceditable_content%2Cvoteup_count%2Creshipment_settings%2Ccomment_permission%2Cmark_infos%2Ccreated_time%2Cupdated_time%2Crelationship.is_authorized%2Cis_author%2Cvoting%2Cis_thanked%2Cis_nothelp%2Cupvoted_followees%3Bdata%5B%2A%5D.author.follower_count%2Cbadge%5B%3F%28type%3Dbest_answerer%29%5D.topics&limit=20&offset=3
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返回的都是JSON数据，很方便获取。但是这里有一个地方需要注意，从这里面取的答案正文数据就是文本数据，不是一个完整的html文件，所以需要在构造一下。

保存的字段

• author_name 回答用户名
• answer_id 答案ID
• question_id 问题ID
• question_title 问题
• vote_up_count 赞同数
• create_time 创建时间
• 答案主体

主脚本：zhihu.py

import os
import re
import json
import requests
import html2text
from parse_content import parse
'''
更多Python学习资料以及源码教程资料，可以在群1136201545免费获取
'''
"""
just for study and fun
Talk is cheap
show me your code
"""

class ZhiHu(object):
    def __init__(self):
         self.request_content = None

    def request(self, url, retry_times=10):
        header = {
            'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36',
            'authorization': 'oauth c3cef7c66a1843f8b3a9e6a1e3160e20',
            'Host': 'www.zhihu.com'
        }
        times = 0
        while retry_times>0:
            times += 1
            print 'request %s, times: %d' %(url, times)
            try:
                ip = 'your proxy ip'
                if ip:
                    proxy = {
                        'http': 'http://%s' % ip,
                        'https': 'http://%s' % ip
                    }
                    self.request_content = requests.get(url, headers=header, proxies=proxy, timeout=10).content
            except Exception, e:
                print e
                retry_times -= 1
            else:
                return self.request_content

    def get_all_answer_content(self, question_id, flag=2):
        first_url_format = 'https://www.zhihu.com/api/v4/questions/{}/answers?sort_by=default&include=data%5B%2A%5D.is_normal%2Cis_collapsed%2Ccollapse_reason%2Cis_sticky%2Ccollapsed_by%2Csuggest_edit%2Ccomment_count%2Ccan_comment%2Ccontent%2Ceditable_content%2Cvoteup_count%2Creshipment_settings%2Ccomment_permission%2Cmark_infos%2Ccreated_time%2Cupdated_time%2Crelationship.is_authorized%2Cis_author%2Cvoting%2Cis_thanked%2Cis_nothelp%2Cupvoted_followees%3Bdata%5B%2A%5D.author.follower_count%2Cbadge%5B%3F%28type%3Dbest_answerer%29%5D.topics&limit=20&offset=3'
        first_url = first_url_format.format(question_id)
        response = self.request(first_url)
        if response:
            contents = json.loads(response)
            print contents.get('paging').get('is_end')
            while not contents.get('paging').get('is_end'):
                for content in contents.get('data'):
                    self.parse_content(content, flag)
                next_page_url = contents.get('paging').get('next').replace('http', 'https')
                contents = json.loads(self.request(next_page_url))
        else:
            raise ValueError('request failed, quit......')

    def get_single_answer_content(self, answer_url, flag=1):
        all_content = {}
        question_id, answer_id = re.findall('https://www.zhihu.com/question/(\d+)/answer/(\d+)', answer_url)[0]

        html_content = self.request(answer_url)
        if html_content:
            all_content['main_content'] = html_content
        else:
            raise  ValueError('request failed, quit......')

        ajax_answer_url = 'https://www.zhihu.com/api/v4/answers/{}'.format(answer_id)
        ajax_content = self.request(ajax_answer_url)
        if ajax_content:
            all_content['ajax_content'] = json.loads(ajax_content)
        else:
            raise  ValueError('request failed, quit......')

        self.parse_content(all_content, flag, )

    def parse_content(self, content, flag=None):
        data = parse(content, flag)
        self.transform_to_markdown(data)

    def transform_to_markdown(self, data):
        content = data['content']
        author_name = data['author_name']
        answer_id = data['answer_id']
        question_id = data['question_id']
        question_title = data['question_title']
        vote_up_count = data['vote_up_count']
        create_time = data['create_time']

        file_name = u'%s--%s的回答[%d].md' % (question_title, author_name,answer_id)
        folder_name = u'%s' % (question_title)

        if not os.path.exists(os.path.join(os.getcwd(),folder_name)):
            os.mkdir(folder_name)
        os.chdir(folder_name)

        f = open(file_name, "wt")
        f.write("-" * 40 + "\n")
        origin_url = 'https://www.zhihu.com/question/{}/answer/{}'.format(question_id, answer_id)
        f.write("## 本答案原始链接: " + origin_url + "\n")
        f.write("### question_title: " + question_title.encode('utf-8') + "\n")
        f.write("### Author_Name: " + author_name.encode('utf-8') + "\n")
        f.write("### Answer_ID: %d" % answer_id + "\n")
        f.write("### Question_ID %d: " % question_id + "\n")
        f.write("### VoteCount: %s" % vote_up_count + "\n")
        f.write("### Create_Time: " + create_time + "\n")
        f.write("-" * 40 + "\n")

        text = html2text.html2text(content.decode('utf-8')).encode("utf-8")
        # 标题
        r = re.findall(r'\*\*(.*?)\*\*', text, re.S)
        for i in r:
            if i != " ":
                text = text.replace(i, i.strip())

        r = re.findall(r'_(.*)_', text)
        for i in r:
            if i != " ":
                text = text.replace(i, i.strip())
        text = text.replace('_ _', '')

        # 图片
        r = re.findall(r'!\[\]\((?:.*?)\)', text)
        for i in r:
            text = text.replace(i, i + "\n\n")

        f.write(text)

        f.close()


if __name__ == '__main__':
    zhihu = ZhiHu()
    url = 'https://www.zhihu.com/question/27621722/answer/105331078'
    zhihu.get_single_answer_content(url)

    # question_id = '27621722'
    # zhihu.get_all_answer_content(question_id)
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zhihu.py为主脚本，内容很简单，发起请求，调用解析函数进行解析，最后再进行保存。

解析函数脚本：parse_content.py

import time
from bs4 import BeautifulSoup
'''
更多Python学习资料以及源码教程资料，可以在群1136201545免费获取
'''
def html_template(data):
    # api content
    html = '''
        <html>
        <head>
        <body>
        %s
        </body>
        </head>
        </html>
        ''' % data
    return html
 
 
def parse(content, flag=None):
    data = {}
    if flag == 1:
        # single
        main_content = content.get('main_content')
        ajax_content = content.get('ajax_content')
 
        soup = BeautifulSoup(main_content.decode("utf-8"), "lxml")
        answer = soup.find("span", class_="RichText CopyrightRichText-richText")
 
        author_name = ajax_content.get('author').get('name')
        answer_id = ajax_content.get('id')
        question_id = ajax_content.get('question').get('id')
        question_title = ajax_content.get('question').get('title')
        vote_up_count = soup.find("meta", itemprop="upvoteCount")["content"]
        create_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(ajax_content.get('created_time')))
 
 
    else:
        # all
        answer_content = content.get('content')
 
        author_name = content.get('author').get('name')
        answer_id = content.get('id')
        question_id = content.get('question').get('id')
        question_title = content.get('question').get('title')
        vote_up_count = content.get('voteup_count')
        create_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(content.get('created_time')))
 
        content = html_template(answer_content)
        soup = BeautifulSoup(content, 'lxml')
        answer = soup.find("body")
 
    print author_name,answer_id,question_id,question_title,vote_up_count,create_time
    # 这里非原创，看了别人的代码，修改了一下
    soup.body.extract()
    soup.head.insert_after(soup.new_tag("body", **{'class': 'zhi'}))
 
    soup.body.append(answer)
 
    img_list = soup.find_all("img", class_="content_image lazy")
    for img in img_list:
        img["src"] = img["data-actualsrc"]
    img_list = soup.find_all("img", class_="origin_image zh-lightbox-thumb lazy")
    for img in img_list:
        img["src"] = img["data-actualsrc"]
    noscript_list = soup.find_all("noscript")
    for noscript in noscript_list:
        noscript.extract()
 
    data['content'] = soup
    data['author_name'] = author_name
    data['answer_id'] = answer_id
    data['question_id'] = question_id
    data['question_title'] = question_title
    data['vote_up_count'] = vote_up_count
    data['create_time'] = create_time
 
    return data
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parse_content.py主要负责构造新的html，然后对其进行解析，获取数据。

测试结果展示

一定要联网！

一定要联网！

一定要联网！