两种方式爬取：Get和Post

主要用urllib.request 包的Request(请求)和urlopen(访问)两个方法

from urllib.request import Request,urlopen

#一个Get请求
url = 'http://www.douban.com'
#设置请求头是模拟浏览器访问反爬虫的网址
headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36'}
res = urlopen(Request(url, headers=headers))
print(res.read().decode('utf-8'))   #read读取的是GBK格式,要设置utf-8

from urllib.request import Request,urlopen
import urllib.parse

#一个Post请求
#这是一个测试Post请求的网址,Post请求需要携带表单数据才能正常访问
url = "http://httpbin.org/post"
headers={"User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36"}
urlencode = urllib.parse.urlencode({"hello": "world"}) #将diect类型数据转换成url表单键值对格式
bytes = bytes(urlencode,encoding="utf-8")      #将字符串转化为byte类型
Request = Request(url, headers=headers, data=bytes, method="POST") #data必须是一个bytes的类型
urlopen1 = urlopen(Request,timeout=2) #urlopen方法参数可以是Request对象，也可以是url等其他参数,timeout超时时间2秒
print(urlopen1.read().decode("utf-8"))

代理爬虫

urllib方式

from urllib.request import Request,urlopen,ProxyHandler,build_opener

#urllib测试代理
url = "http://httpbin.org/get"
headers={"user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36"}
request = Request(url=url,headers=headers)
#设置Handler代理ip地址
httpproxy_handler = ProxyHandler({"http" : "122.51.231.113:8080",
                                  "https" : "122.51.231.113:8080"})
#用handler代理对象构建opener对象
opener = build_opener(httpproxy_handler)
#使用opener的open方法进行网页访问
response = opener.open(request)
print(response.read().decode('utf-8'))

requests方式

import requests
#requests 请求方式

headers={"user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.190 Safari/537.36"}
#设代理
proxies={"http" : "http://122.51.231.113:8080",
         "https" : "https://122.51.231.113:8080"}
get = requests.get("http://www.baidu.com",headers,proxies=proxies).text
print(get)

下载文件(图片)

import requests
import os
    get = requests.get('https://img0.baidu.com/it/u=1986451467,394304688&fm=26&fmt=auto&gp=0.jpg')
    os.mkdir('jpg') #创建目录
    with open('jpg/hello.jpg','wb') as o:
        o.write(get.content)    #将图片写入
        print('下载完成')
    print("hello,python")