Python爬虫新手教程：知乎文章图片爬取器!

作者: 14e61d025165 | 来源:发表于2019-07-27 14:51 被阅读1次

Python爬虫新手教程：知乎文章图片爬取器!
Python爬虫新手教程：知乎文章图片爬取器
Python爬虫新手教程：知乎文章图片爬取器
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1. 知乎文章图片爬取器之二博客背景

昨天写了知乎文章图片爬取器的一部分代码，针对知乎问题的答案json进行了数据抓取，博客中出现了部分写死的内容，今天把那部分信息调整完毕，并且将图片下载完善到代码中去。

首先，需要获取任意知乎的问题，只需要你输入问题的ID，就可以获取相关的页面信息，比如最重要的合计有多少人回答问题。

问题ID为如下标红数字

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编写代码，下面的代码用来检测用户输入的是否是正确的ID，并且通过拼接URL去获取该问题下面合计有多少答案。

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<pre spellcheck="false" style="box-sizing: border-box; margin: 5px 0px; padding: 5px 10px; border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-weight: 400; font-stretch: inherit; font-size: 16px; line-height: inherit; font-family: inherit; vertical-align: baseline; cursor: text; counter-reset: list-1 0 list-2 0 list-3 0 list-4 0 list-5 0 list-6 0 list-7 0 list-8 0 list-9 0; background-color: rgb(240, 240, 240); border-radius: 3px; white-space: pre-wrap; color: rgb(34, 34, 34); letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">import requests
import re
import pymongo
import time
DATABASE_IP = '127.0.0.1'
DATABASE_PORT = 27017
DATABASE_NAME = 'sun'
client = pymongo.MongoClient(DATABASE_IP,DATABASE_PORT)
db = client.sun
db.authenticate("dba", "dba")
collection = db.zhihuone # 准备插入数据
BASE_URL = "https://www.zhihu.com/question/{}"
def get_totle_answers(article_id):
headers = {
"user-agent": "需要自己补全 Mozilla/5.0 (Windows NT 10.0; WOW64)"
}
with requests.Session() as s:
with s.get(BASE_URL.format(article_id),headers=headers,timeout=3) as rep:
html = rep.text
pattern =re.compile( '<meta itemProp="answerCount" content="(\d*?)"/>')
s = pattern.search(html)
print("查找到{}条数据".format(s.groups()[0]))
return s.groups()[0]
if name == 'main':
# 用死循环判断用户输入的是否是数字
article_id = ""
while not article_id.isdigit():
article_id = input("请输入文章ID：")
totle = get_totle_answers(article_id)
if int(totle)>0:
zhi = ZhihuOne(article_id,totle)
zhi.run()
else:
print("没有任何数据！")
</pre>

完善图片下载部分，图片下载地址在查阅过程中发现，存在json字段的 content 中，我们采用简单的正则表达式将他匹配出来。细节如下图展示

<tt-image data-tteditor-tag="tteditorTag" contenteditable="false" class="syl1564210198830" data-render-status="finished" data-syl-blot="image" style="box-sizing: border-box; cursor: text; color: rgb(34, 34, 34); font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", "Helvetica Neue", Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial; display: block;">

image

编写代码吧，下面的代码注释请仔细阅读，中间有一个小BUG，需要手动把pic3修改为pic2这个地方目前原因不明确，可能是我本地网络的原因，还有请在项目根目录先创建一个 imgs 的文件夹，用来存储图片

<pre spellcheck="false" style="box-sizing: border-box; margin: 5px 0px; padding: 5px 10px; border: 0px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-variant-numeric: inherit; font-variant-east-asian: inherit; font-weight: 400; font-stretch: inherit; font-size: 16px; line-height: inherit; font-family: inherit; vertical-align: baseline; cursor: text; counter-reset: list-1 0 list-2 0 list-3 0 list-4 0 list-5 0 list-6 0 list-7 0 list-8 0 list-9 0; background-color: rgb(240, 240, 240); border-radius: 3px; white-space: pre-wrap; color: rgb(34, 34, 34); letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">def download_img(self,data):
## 下载图片
for item in data["data"]:
content = item["content"]
pattern = re.compile('<noscript>(.?)</noscript>')
imgs = pattern.findall(content)
if len(imgs) > 0:
for img in imgs:
match = re.search('<img src="(.?)"', img)
download = match.groups()[0]
download = download.replace("pic3", "pic2") # 小BUG,pic3的下载不到
print("正在下载{}".format(download), end="")
try:
with requests.Session() as s:
with s.get(download) as img_down:
# 获取文件名称
file = download[download.rindex("/") + 1:]
content = img_down.content
with open("imgs/{}".format(file), "wb+") as f: # 这个地方进行了硬编码
f.write(content)
print("图片下载完成", end="\n")
except Exception as e:
print(e.args)
else:
pass
</pre>

运行结果为

<tt-image data-tteditor-tag="tteditorTag" contenteditable="false" class="syl1564210198837" data-render-status="finished" data-syl-blot="image" style="box-sizing: border-box; cursor: text; color: rgb(34, 34, 34); font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", "Helvetica Neue", Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial; display: block;">

image

然后在玩知乎的过程中，发现了好多好问题

<tt-image data-tteditor-tag="tteditorTag" contenteditable="false" class="syl1564210198840" data-render-status="finished" data-syl-blot="image" style="box-sizing: border-box; cursor: text; color: rgb(34, 34, 34); font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", "Helvetica Neue", Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial; display: block;">

image <input class="pgc-img-caption-ipt" placeholder="图片描述(最多50字)" value="" style="box-sizing: border-box; outline: 0px; color: rgb(102, 102, 102); position: absolute; left: 187.5px; transform: translateX(-50%); padding: 6px 7px; max-width: 100%; width: 375px; text-align: center; cursor: text; font-size: 12px; line-height: 1.5; background-color: rgb(255, 255, 255); background-image: none; border: 0px solid rgb(217, 217, 217); border-radius: 4px; transition: all 0.2s cubic-bezier(0.645, 0.045, 0.355, 1) 0s;"></tt-image> <tt-image data-tteditor-tag="tteditorTag" contenteditable="false" class="syl1564210198843" data-render-status="finished" data-syl-blot="image" style="box-sizing: border-box; cursor: text; color: rgb(34, 34, 34); font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", "Helvetica Neue", Arial, sans-serif; font-size: 16px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: pre-wrap; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255); text-decoration-style: initial; text-decoration-color: initial; display: block;">