爬虫学习：分析Ajax请求抓取今日头条街拍美图

需要说明的是并没爬取成功，怀疑是网站设置了反爬虫机制：
代码如下：

import requests
from urllib.parse import urlencode
from requests import exceptions
import json
import os
from hashlib import md5
from multiprocessing.pool import Pool


def get_page(offset):
    params = {
        'aid': '24',
        'app_name': 'web_search',
        'offset': offset,
        'format': 'json',
        'keyword': '街拍',
        'autoload': 'true',
        'count': '20',
        'en_qc': '1',
        'cur_tab': '1'
    }
    headers = {
        'cookie': 'tt_webid = 6735572958447977996;WEATHER_CITY = % E5 % 8C % 97 % E4 % BA % AC;tt_webid = 6735572958447977996;csrftoken = c3e55dfe0045ef079b496f27dea17ad8;sso_uid_tt = 7c1088ddfdbc75cf58c03def3e61ffd5;toutiao_sso_user = 4c6dc455a3e3f01e1ccf726edeca4c85;login_flag = 580d00027b658521d3d2df09cfe584d4;sessionid = 512a4bcfb5d3cf26a9cd6c132fdb5f46;uid_tt = e8cd26d92023013dfba19509a87b9d42;sid_tt = 512a4bcfb5d3cf26a9cd6c132fdb5f46;sid_guard = "512a4bcfb5d3cf26a9cd6c132fdb5f46|1568712418|15552000|Sun\054 15-Mar-2020 09:26:58 GMT";s_v_web_id = 674345bdfb21d1c64a2c5a0cb15cce32;tasessionId = e03vknqeo1569288824259',
        'User-Agent': 'Mozilla / 5.0(Windows NT 10.0;Win64;x64) AppleWebKit / 537.36(KHTML, likeGecko) Chrome / 76.0.3809.132Safari / 537.36 '
    }
    url = 'https://www.toutiao.com/api/search/content/?'+urlencode(params)
    try:

        response = requests.get(url, params=params)
        if response.status_code == 200:
            return response.text
    except requests.ConnectionError:
        return None


def get_images(json):
    if json.get('data'):
        for item in json.get('data'):
            title = item.get('title')
            images = item.get('image_detail')
            for image in images:
                yield {
                    'image': image.get('url'),
                    'title': title
                }


def save_image(item):
    if not os.path.exists(item.get('title')):
        os.mkdir(item.get('title'))

    try:
        headers = {
            'cookie': 'tt_webid = 6735572958447977996;WEATHER_CITY = % E5 % 8C % 97 % E4 % BA % AC;tt_webid = 6735572958447977996;csrftoken = c3e55dfe0045ef079b496f27dea17ad8;sso_uid_tt = 7c1088ddfdbc75cf58c03def3e61ffd5;toutiao_sso_user = 4c6dc455a3e3f01e1ccf726edeca4c85;login_flag = 580d00027b658521d3d2df09cfe584d4;sessionid = 512a4bcfb5d3cf26a9cd6c132fdb5f46;uid_tt = e8cd26d92023013dfba19509a87b9d42;sid_tt = 512a4bcfb5d3cf26a9cd6c132fdb5f46;sid_guard = "512a4bcfb5d3cf26a9cd6c132fdb5f46|1568712418|15552000|Sun\054 15-Mar-2020 09:26:58 GMT";s_v_web_id = 674345bdfb21d1c64a2c5a0cb15cce32;tasessionId = e03vknqeo1569288824259',
            'User-Agent': 'Mozilla / 5.0(Windows NT 10.0;Win64;x64) AppleWebKit / 537.36(KHTML, likeGecko) Chrome / 76.0.3809.132Safari / 537.36 '
        }
        response = requests.get(item.get('image'))
        if response.status_code == 200:
            file_path = '{0}/{1}{2}'.format(item.get('title'), md5(response.content).hexdigest(), '.jpg')
            if not os.path.exists(file_path):
                with open(file_path, 'wb') as f:
                    f.write(response.content)
            else:
                print('Already Downloaded', file_path)

    except requests.ConnectionError:
        print('Failed to Save Image!')


def main(offset):
    json = get_page(offset)
    for item in get_images(json):
        print(item)
        save_image(item)


GROUP_START = 1
GROUP_END = 20


if __name__ == 'main':
    pool = Pool()
    groups = ([x*20 for x in range(GROUP_START, GROUP_END+1)])
    pool.map(main, groups)
    pool.close()
    pool.join()

运行结果不符合预期，如果有有看到代码块的问题还请多多指教！