写个知乎回答照片爬虫吧

爬的话当然得爬好看的咯～

#coding: utf-8

import time
import os
import re

import requests
from lxml import etree

DIR = "image"      # 文件存放目录名，相对于当前目录
#每次请求知乎的讨论列表长度，不建议设定太长，注意节操
LIMIT = 5

#这是话题『美女』的 ID
SOURCE = "19552207"

USER_AGENT = "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/534.55.3 (KHTML, like Gecko) Version/5.1.5 Safari/534.55.3"
REFERER = "https://www.zhihu.com/topic/%s/newest" % SOURCE
BASE_URL = "https://www.zhihu.com/api/v4/topics/%s/feeds/timeline_activity"
#初始请求 url 附带的请求参数
URL_QUERY = "?include=data%5B%3F%28target.type%3Dtopic_sticky_module%29%5D.target.data%5B%3F%28target.type%3Danswer%29%5D.target.content%2Crelationship.is_authorized%2Cis_author%2Cvoting%2Cis_thanked%2Cis_nothelp%3Bdata%5B%3F%28target.type%3Dtopic_sticky_module%29%5D.target.data%5B%3F%28target.type%3Danswer%29%5D.target.is_normal%2Ccomment_count%2Cvoteup_count%2Ccontent%2Crelevant_info%2Cexcerpt.author.badge%5B%3F%28type%3Dbest_answerer%29%5D.topics%3Bdata%5B%3F%28target.type%3Dtopic_sticky_module%29%5D.target.data%5B%3F%28target.type%3Darticle%29%5D.target.content%2Cvoteup_count%2Ccomment_count%2Cvoting%2Cauthor.badge%5B%3F%28type%3Dbest_answerer%29%5D.topics%3Bdata%5B%3F%28target.type%3Dtopic_sticky_module%29%5D.target.data%5B%3F%28target.type%3Dpeople%29%5D.target.answer_count%2Carticles_count%2Cgender%2Cfollower_count%2Cis_followed%2Cis_following%2Cbadge%5B%3F%28type%3Dbest_answerer%29%5D.topics%3Bdata%5B%3F%28target.type%3Danswer%29%5D.target.content%2Crelationship.is_authorized%2Cis_author%2Cvoting%2Cis_thanked%2Cis_nothelp%3Bdata%5B%3F%28target.type%3Danswer%29%5D.target.author.badge%5B%3F%28type%3Dbest_answerer%29%5D.topics%3Bdata%5B%3F%28target.type%3Darticle%29%5D.target.content%2Cauthor.badge%5B%3F%28type%3Dbest_answerer%29%5D.topics%3Bdata%5B%3F%28target.type%3Dquestion%29%5D.target.comment_count&limit=" + str(LIMIT)

#指定 url，获取对应原始内容 / 图片
def fetch_image(url):
    try:
        headers = {
                "User-Agent": USER_AGENT,
                "Referer": REFERER,
                }
        s = requests.get(url, headers=headers)
    except Exception as e:
        print("fetch last activities fail. " + url)
        raise e

    return s.content

#指定 url，获取对应 JSON 返回 / 话题列表
def fetch_activities(url):
    try:
        headers = {
                "User-Agent": USER_AGENT,
                "Referer": REFERER,
                }
        s = requests.get(url, headers=headers)
    except Exception as e:
        print("fetch last activities fail. " + url)
        raise e

    return s.json()

#处理返回的话题列表
def process_activities(datums):
    for data in datums["data"]:

        target = data["target"]
        if "content" not in target or "question" not in target or "author" not in target:
            continue

        #解析列表中每一个元素的内容
        html = etree.HTML(target["content"])

        seq = 0

        #question_url = target["question"]["url"]
        question_title = target["question"]["title"]

        author_name = target["author"]["name"]
        #author_id = target["author"]["url_token"]

        print("current answer: " + question_title + " author: " + author_name)

        #获取所有图片地址
        images = html.xpath("//img/@src")
        for image in images:
            if not image.startswith("http"):
                continue
            s = fetch_image(image)
            
            filename =  question_title + ("--%d" % seq) + ".jpg"
            filename = re.sub(r'(?u)[^-\w.]', '_', filename)
            #注意文件名的处理，不同平台的非法字符不一样，这里只做了简单处理，特别是 author_name / question_title 中的内容
            seq = seq + 1
            with open(os.path.join(DIR, filename), "wb") as fd:
                fd.write(s)


    if not datums["paging"]["is_end"]:
        #获取后续讨论列表的请求 url
        return datums["paging"]["next"]
    else:
        return None

def get_valid_filename(s):
    s = str(s).strip().replace(' ', '_')
    return re.sub(r'(?u)[^-\w.]', '_', s)


def init_env():
    if not os.path.exists(DIR):
        os.makedirs(DIR)

init_env()

url = BASE_URL % SOURCE + URL_QUERY
while url is not None:
    print("current url: " + url)
    datums = fetch_activities(url)
    url = process_activities(datums)
    #注意节操，爬虫休息间隔不要调小
    time.sleep(5)