学习python 抓取知乎指定回答下视频的方法

{
	"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": {}
}

# -*- 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())