还是涉及到django的请求生命周期。middle ware 请求穿过中间件到达url，再经过中间件返回给用户。
简单实例
django项目根目录新建一个Middle文件夹，再新建一个test.py文件
在test文件中写入；其中的类必须继承 from django.utils.deprecation import MiddlewareMixin
from django.utils.deprecation import MiddlewareMixin class M1(MiddlewareMixin): def process_request(self, request): print(\'m1\') def process_response(self, request, response): print(\'m1_r\') return response class M2(MiddlewareMixin): def process_request(self, request): print(\'m2\') def process_response(self, request, response): print(\'m2_r\') return response class M3(MiddlewareMixin): def process_request(self, request): print(\'m3\') def process_response(self, request, response): print(\'m3_r\') return response