学习python 抓取知乎指定回答下视频的方法

前言

现在知乎允许上传视频，奈何不能下载视频，好气哦，无奈之下研究一下了，然后撸了代码，方便下载视频保存。

接下来以 猫为什么一点也不怕蛇？ 回答为例，分享一下整个下载过程。

相关学习推荐：python视频教程

调试一下

打开 F12, 找到光标，如下图：

然后将光标移动到视频上。如下图：

咦这是什么？视野中出现了一条神秘的链接: https://www.zhihu.com/video/xxxxx，让我们将这条链接复制到浏览器上，然后打开：

似乎这就是我们要找的视频，不要着急，让我们看一看，网页的请求，然后你会发现一个很有意思的请求(重点来了):

让我们自己看一下数据吧:

{ 	"playlist": { 		"ld": { 			"width": 360, 			"format": "mp4", 			"play_url": "https://vdn.vzuu.com/LD/05fc411e-d8e0-11e8-bb8b-0242ac112a0b.mp4?auth_key=1541477643-0-0-987c2c504d14ab1165ce2ed47759d927&expiration=1541477643&disable_local_cache=1", 			"duration": 17, 			"size": 1123111, 			"bitrate": 509, 			"height": 640 		}, 		"hd": { 			"width": 720, 			"format": "mp4", 			"play_url": "https://vdn.vzuu.com/HD/05fc411e-d8e0-11e8-bb8b-0242ac112a0b.mp4?auth_key=1541477643-0-0-8b8024a22a62f097ca31b8b06b7233a1&expiration=1541477643&disable_local_cache=1", 			"duration": 17, 			"size": 4354364, 			"bitrate": 1974, 			"height": 1280 		}, 		"sd": { 			"width": 480, 			"format": "mp4", 			"play_url": "https://vdn.vzuu.com/SD/05fc411e-d8e0-11e8-bb8b-0242ac112a0b.mp4?auth_key=1541477643-0-0-5948c2562d817218c9a9fc41abad1df8&expiration=1541477643&disable_local_cache=1", 			"duration": 17, 			"size": 1920976, 			"bitrate": 871, 			"height": 848 		} 	}, 	"title": "", 	"duration": 17, 	"cover_info": { 		"width": 720, 		"thumbnail": "https://pic2.zhimg.com/80/v2-97b9435a0c32d01c7c931bd00120327d_b.jpg", 		"height": 1280 	}, 	"type": "video", 	"id": "1039146361396174848", 	"misc_info": {} }

没错了，我们要下载的视频就在这里面，其中 ld 代表普清,sd 代表标清, hd 代表高清，把相应链接再次在浏览器打开，然后右键保存就可以下载视频了。

代码

知道整个流程是什么样子，接下来撸代码的过程就简单了，这里就不过再做过多解释了，直接上代码:

# -*- encoding: utf-8 -*-  import re import requests import uuid import datetime   class DownloadVideo:    __slots__ = [     'url', 'video_name', 'url_format', 'download_url', 'video_number',     'video_api', 'clarity_list', 'clarity'   ]    def __init__(self, url, clarity='ld', video_name=None):     self.url = url     self.video_name = video_name     self.url_format = "https://www.zhihu.com/question/d+/answer/d+"     self.clarity = clarity     self.clarity_list = ['ld', 'sd', 'hd']     self.video_api = 'https://lens.zhihu.com/api/videos'    def check_url_format(self):     pattern = re.compile(self.url_format)     matches = re.match(pattern, self.url)     if matches is None:       raise ValueError(         "链接格式应符合:https://www.zhihu.com/question/{number}/answer/{number}"       )     return True    def get_video_number(self):     try:       headers = {         'User-Agent':         'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Safari/537.36'       }       response = requests.get(self.url, headers=headers)       response.encoding = 'utf-8'       html = response.text       video_ids = re.findall(r'data-lens-id="(d+)"', html)       if video_ids:         video_id_list = list(set([video_id for video_id in video_ids]))         self.video_number = video_id_list[0]         return self       raise ValueError("获取视频编号异常:{}".format(self.url))     except Exception as e:       raise Exception(e)    def get_video_url_by_number(self):     url = "{}/{}".format(self.video_api, self.video_number)      headers = {}     headers['Referer'] = 'https://v.vzuu.com/video/{}'.format(       self.video_number)     headers['Origin'] = 'https://v.vzuu.com'     headers[       'User-Agent'] = 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.67 Safari/537.36'     headers['Content-Type'] = 'application/json'      try:       response = requests.get(url, headers=headers)       response_dict = response.json()       if self.clarity in response_dict['playlist']:         self.download_url = response_dict['playlist'][           self.clarity]['play_url']       else:         for clarity in self.clarity_list:           if clarity in response_dict['playlist']:             self.download_url = response_dict['playlist'][               self.clarity]['play_url']             break       return self     except Exception as e:       raise Exception(e)    def get_video_by_video_url(self):     response = requests.get(self.download_url)     datetime_str = datetime.datetime.now().strftime("%Y-%m-%d %H-%M-%S")     if self.video_name is not None:       video_name = "{}-{}.mp4".format(self.video_name, datetime_str)     else:       video_name = "{}-{}.mp4".format(str(uuid.uuid1()), datetime_str)     path = "{}".format(video_name)     with open(path, 'wb') as f:       f.write(response.content)    def download_video(self):      if self.clarity not in self.clarity_list:       raise ValueError("清晰度参数异常,仅支持:ld(普清),sd(标清),hd(高清)")      if self.check_url_format():       return self.get_video_number().get_video_url_by_number().get_video_by_video_url()   if __name__ == '__main__':   a = DownloadVideo('https://www.zhihu.com/question/53031925/answer/524158069')   print(a.download_video())

结语

代码还有优化空间，这里面我只是下载了回答中的第一个视频，理论上应该存在一个回答下可以有多个视频的。如果还有什么疑问或者建议，可以多多交流。

相关学习推荐：python视频教程