一 介绍

爬虫-请求库之request
#介绍:使用requests可以模拟浏览器的请求,比起之前用到的urllib,requests模块的api更加便捷(本质就是封装了urllib3)

#注意:requests库发送请求将网页内容下载下来以后,并不会执行js代码,这需要我们自己分析目标站点然后发起新的request请求

#安装:pip3 install requests

#各种请求方式:常用的就是requests.get()和requests.post()
>>> import requests
>>> r = requests.get('https://api.github.com/events')
>>> r = requests.post('http://httpbin.org/post', data = {'key':'value'})
>>> r = requests.put('http://httpbin.org/put', data = {'key':'value'})
>>> r = requests.delete('http://httpbin.org/delete')
>>> r = requests.head('http://httpbin.org/get')
>>> r = requests.options('http://httpbin.org/get')

#建议在正式学习requests前,先熟悉下HTTP协议
http://www.cnblogs.com/linhaifeng/p/6266327.html
爬虫-请求库之request

官网链接:http://docs.python-requests.org/en/master/

二 基于GET请求

1、基本请求

import requests
response=requests.get('http://dig.chouti.com/')
print(response.text)

2、带参数的GET请求->params

#在请求头内将自己伪装成浏览器,否则百度不会正常返回页面内容
import requests
response=requests.get('https://www.baidu.com/s?wd=python&pn=1',
                      headers={
                        'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36',
                      })
print(response.text)


#如果查询关键词是中文或者有其他特殊符号,则不得不进行url编码
from urllib.parse import urlencode
wd='egon老师'
encode_res=urlencode({'k':wd},encoding='utf-8')
keyword=encode_res.split('=')[1]
print(keyword)
# 然后拼接成url
url='https://www.baidu.com/s?wd=%s&pn=1' %keyword

response=requests.get(url,
                      headers={
                        'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36',
                      })
res1=response.text

自己拼接GET参数

#上述操作可以用requests模块的一个params参数搞定,本质还是调用urlencode
from urllib.parse import urlencode
wd='egon老师'
pn=1

response=requests.get('https://www.baidu.com/s',
                      params={
                          'wd':wd,
                          'pn':pn
                      },
                      headers={
                        'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.75 Safari/537.36',
                      })
res2=response.text

#验证结果,打开a.html与b.html页面内容一样
with open('a.html','w',encoding='utf-8') as f:
    f.write(res1) 
with open('b.html', 'w', encoding='utf-8') as f:
    f.write(res2)

params参数的使用