python接口自动化： CAS系统验证，自动完成登录并获取token，遇到302请求重定向设置（requests模块 allow_redirects=False）即可

import requests
import re

 import requests
 import re 

 class Crm_token(object):
     try:
         username=int(input("请输入登录手机号：\n"))
         password=input("请输入登录密码：\n")
     except Exception as error:
         print("登录信息输入错误，错误信息%s"%(error))
     def __init__(self):
         self.url_login_in='http://xxxx'
         self.login_server='http://xxx/cas/eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.Imh0dHA6XC9cLzQ3LjEwNi4xNzguNDk6ODA4MlwvIg.8HSZHPyW7byY-MOVtFhdsiy_cpigL3RcStk9hGa8Su8'
         self.return_url="http://xxxx/?return_url=xxx/"
     def get_token(self,username=username,password=password):
         headers_check_login={"Content-Type":"application/x-www-form-urlencoded"}
         url_check_login='http://xxxx/Auth/checkLogin' #用户名密码验证接口
         check_login_data='username=%d&password=%s'%(username,password)
         request_check_login=requests.post(url=url_check_login,headers=headers_check_login,data=check_login_data)
         response_login_message=request_check_login.json()
         # print(response_login_message)
         if response_login_message['msg'] == '成功' and response_login_message['code']==200:
             print('begin---login---')
             try:
                 session=requests.Session() #建立session会话
                 headers1={"User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3493.3 Safari/537.36",
                 "Referer":self.return_url,"Content-Type":'application/x-www-form-urlencoded'}
                 url_login_1=self.url_login_in+'/CAS_server/login?action=getlt&service=%s&callback=jQuery33105752563290575323_1551706407492&_=1551706407493'%(self.login_server)
                 request1=session.request("GET",url=url_login_1,headers=headers1,data=None) #登录前动态参数获取url
                 response1=request1.text
                 get_shouquan_str1=eval(re.search('{.*}',response1).group()) #匹配出字典内的内容并用eval方法将str转换为dict
                 get_lt=get_shouquan_str1['lt'] #提取授权参数1
                 get_execution=get_shouquan_str1['execution'] #提取授权参数2
                 cookies_login_1=request1.cookies.get_dict() #获取cookie：JSESSIONID
                 seesionId=cookies_login_1['JSESSIONID']
                 requestSeesionId=str('JSESSIONID='+seesionId) #拼接为请求可用的cookie值
                 # print(requestSeesionId)
                 # print(get_lt)
                 # print(get_execution)
                 headers2={"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
                 "User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3493.3 Safari/537.36",
                 "Content-Type":'application/x-www-form-urlencoded',"Cookie":requestSeesionId,"Referer":self.return_url}
                 url_login_2=self.url_login_in+'/CAS_server/login?service=%s'%(self.login_server)
                 #请求信息头必须传cookie，否则会一直返回登录页面
                 login_data='lt=%s&execution=%s&_eventId=submit&username=%s&password=%s&submit=登录'%(get_lt,get_execution,username,password)
                 # login_data='lt=%s&execution=%s&_eventId=submit&username=%d&password=%s'%(get_lt,get_execution,username,password)
                 #登录body，将获取到对的两个动态参数也传进去
                 request2=session.post(url=url_login_2,headers=headers2,data=login_data.encode(),allow_redirects=False)
                 #allow_redirects=False,禁止请求重定向：为了获取重定向url，requests模块默认请求重定向
                 # request2=session.post(url=url_login_2,headers=headers2,data=login_data.encode(),allow_redirects=True)
                 response2=request2.text
                 responseHeaders2=request2.headers #获取reponse header
                 # print(response2)
                 # print(responseHeaders2)
                 url_chongdingxiang_st=responseHeaders2["location"] #获取重定向url
                 requests3=session.get(url=url_chongdingxiang_st,headers=headers2,data=None,allow_redirects=False)
                 response3=requests3.text
                 responseHeaders3=requests3.headers
                 php_session_cookie=responseHeaders3['Set-Cookie'] #获取php_session
                 php_session_id=re.search("(\w*\W*\w*)",php_session_cookie).group() #用正则匹配出所需要的php_session_id
                 # print(php_session_id)
                 # print(responseHeaders3)
                 url_chongdingxiang_get_ticket=responseHeaders3['location']#获取重定向url
                 headers3={"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
                 "User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3493.3 Safari/537.36",
                 "Content-Type":'application/x-www-form-urlencoded',"Set-Cookie":php_session_id,"Referer":self.return_url}
                 requests4=session.get(url=url_chongdingxiang_get_ticket,headers=headers3,data=None,allow_redirects=False)
                 response4=requests4.text
                 responseHeaders4=requests4.headers
                 # print(responseHeaders4)
                 url_chongdingxiang_ticket=responseHeaders4['location'] #获取重定向url
                 requests5=session.get(url=url_chongdingxiang_ticket,headers=headers3,data=None,allow_redirects=False)
                 response5=requests5.text
                 responseHeaders5=requests5.headers
                 # print(responseHeaders5)
                 # print(response5)
                 ticket_data=re.search('(ticket.*)',url_chongdingxiang_ticket).group() #用正则匹配出ticket以及对应的value
                 headers4={"Accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8",
                 "User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3493.3 Safari/537.36",
                 "Content-Type":'application/x-www-form-urlencoded',"Referer":url_chongdingxiang_ticket} #将headers来源地址更改为url_chongdingxiang_ticket
                 url_get_token='http://xxxx/Auth/login' #登录接口
                 requests_get_token=session.post(url=url_get_token,headers=headers3,data=ticket_data)
                 reponse6=requests_get_token.json()
                 crm_system_token=reponse6['data']['token']
                 print('login---susscess---')
                 print('当前登陆手机号为:%s,token为:\n%s'%(username,crm_system_token))
                 return crm_system_token
             except BaseException as error:
                 print('登录错误，token获取失败，\n错误信息：%s'%(error))
         else:
             print(response_login_message)

 if __name__=="__main__":
     tk=Crm_token()
     tk.get_token()