django - (七) 中间件的处理

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django - (七) 中间件的处理

比如这里要新增一个统计响应时间的功能

1. 新建一个middlewares.py (student_sys/student/middlewares.py)

   import time
   
   from django.urls import reverse
   from django.utils.deprecation import MiddlewareMixin
   
   class TimeItMiddleware(MiddlewareMixin):
       def process_request(self,request):
           strs = "1. 处理requset请求，第一个被调用，"
           "处理request中认证头之类"
           print(strs)
           return
       def process_view(self,request,func,*args,**kwargs):
           strs = "2. 用于view处理,其中func即是调用的view"
           print(strs)
           if request.path != reverse('index'):
               return None
           start = time.time()
           #这里调用了view做处理
           response  = func(request)
           costed = time.time() - start
           print("process view used  %d seconds" % (costed,))
           return response
   
       def process_exception(self,request,Exception):
           strs = "0. 用来处理全部流程中的异常"
           print(strs)
           pass
   
       def process_template_response(self,request,response):
           strs = "3. 如果处理渲染模板使用了render,就会调用到这里"
           print(strs)
           return response
   
       def process_response(self,request,response):
           strs = "4. 所有的流程执行完后会返回response给浏览器,在返回之前会调用到这里"
           print(strs)
           return response
   

2. 修改setting.py

   MIDDLEWARE = [
       'student.middlewares.TimeItMiddleware',
   
       'django.middleware.security.SecurityMiddleware',
       'django.contrib.sessions.middleware.SessionMiddleware',
       'django.middleware.common.CommonMiddleware',
       'django.middleware.csrf.CsrfViewMiddleware',
       'django.contrib.auth.middleware.AuthenticationMiddleware',
       'django.contrib.messages.middleware.MessageMiddleware',
       'django.middleware.clickjacking.XFrameOptionsMiddleware',
   ]
   

3. 在浏览器上刷新页面观察后台输出