爬虫基础

爬虫概述

爬虫
    善：不破坏被爬取的网站的资源
    恶：影响网站的正常运营（抢票，秒杀，使网站资源宕机）

爬虫的矛与盾
    反爬机制
    反反爬策略
    robots.txt协议

第一个爬虫

from urllib.request import urlopen

url = "http://www.baidu.com"

resp = urlopen(url)
content = resp.read().decode("utf-8")

# open("test.html", mode="w", encoding="utf-8").write(content)
open("test.html", mode="r", encoding="utf-8").read()

requests 模块

需要先安装requests

pip install requests

如果下载过慢，可更改源

# requests 测试
import requests

url = "http://www.baidu.com"
rest = requests.get(url)
rest.encoding = "utf-8"
print(rest.text)

get 请求

import requests

content = input("请输入您要搜索的内容：")
url = f"https://www.sogou.com/web?query={content}"

headers = {
    # 添加一个请求头信息 UA
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36 Edg/112.0.1722.39"
}

rest = requests.get(url, headers = headers)
print(rest.text)

post 请求

import requests

url = "https://fanyi.baidu.com/sug"

content = {
    "kw" : input("test")
}

rest = requests.post(url, data=content)
print(rest.json())