重定向就是网络请求被重新定个方向转到了其它位置
二、为什么要做重定向
网页重定向的情况一般有：网站调整（如网页目录结构变化）、网页地址改变、网页扩展名（.php、.html、.asp）的改变、当一个网站注册了多个域名的时候。这些情况下都需要进行网页的重定向。不做重定向的话就容易出现404错误（如访问网上提供的网页url经常报404错误，就是有可能url地址改变了但没有做重定向导致的。）
三、Python+requests重定向操作
1、重定向分：301 redirect---》永久性重定向、302 redirect---》暂时性重定向，比如下图的302永久性重定向
2、追踪重定向
import requests
url = 'http://home.cnblogs.com/u/xswt/'
r = requests.get(url,params=None,headers={'Content-Type':'application/json'})
print(r.history)#history追踪页面重定向历史
运行结果：
[<Response [301]>, <Response [302]>, <Response [302]>, <Response [302]>]
#可以看到该请求做了多次重定向
3、Python+requests获取重定向的url地址：
import requests
url = 'http://home.cnblogs.com/u/xswt/'
r = requests.get(url,headers={"Content-Type":"application/json"})
reditList = r.history#可以看出获取的是一个地址序列
print(f'获取重定向的历史记录：{reditList}')
print(f'获取第一次重定向的headers头部信息：{reditList[0].headers}')
print(f'获取重定向最终的url：{reditList[len(reditList)-1].headers["location"]}')
运行结果：
获取重定向的历史记录：[<Response [301]>, <Response [302]>, <Response [302]>, <Response [302]>]
获取第一次重定向的headers头部信息：{'Date': 'Fri, 06 Sep 2019 06:53:05 GMT', 'Content-Length': '0', 'Connection': 'keep-alive', 'Location': 'https://home.cnblogs.com/u/xswt/'}
获取重定向最终的url：https://account.cnblogs.com/signin?returnUrl=http%3a%2f%2fhome.cnblogs.com%2fu%2fxswt%2f
4、Python+requests重启和禁止重定向
禁止重定向（all_redirects=False）
import
requests
url
=
'
http://home.cnblogs.com/u/xswt/
'
r
= requests.get(url,headers={
"
Content-Type
"
:
"
application/json
"
},allow_redirects=
False)
print
(r.status_code)
print
(r.text)
运行结果：
重启重定向
import
requests
url
=
'
http://home.cnblogs.com/u/xswt/
'
r
= requests.get(url,headers={
"
Content-Type
"
:
"
application/json
"
},allow_redirects=
True)
print
(r.status_code)
print
(r.text)
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