Django之中间件

django 中的中间件（middleware），在django中，中间件其实就是一个类，在请求到来和结束后，django会根据自己的规则在合适的时机执行中间件中相应的方法。

在django项目的settings模块中，有一个 MIDDLEWARE_CLASSES 变量，其中每一个元素就是一个中间件，如下图。

与mange.py在同一目录下的文件夹 wupeiqi/middleware下的auth.py文件中的Authentication类

中间件中可以定义四个方法，分别是：

• process_request(self,request)
• process_view(self, request, callback, callback_args, callback_kwargs)
• process_template_response(self,request,response)
• process_exception(self, request, exception)
• process_response(self, request, response)

以上方法的返回值可以是None和HttpResonse对象，如果是None，则继续按照django定义的规则向下执行，如果是HttpResonse对象，则直接将该对象返回给用户。

自定义中间件

1、settings.py

from django.middleware.common import CommonMiddleware

MIDDLEWARE = [
    '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',
    'md.M1',
    'md.M2',
]

 2、views.py

from django.shortcuts import render,HttpResponse,redirect

# Create your views here.
def test(request):
    print("test===")
    return HttpResponse("...666")

3、新建md.py

#!/usr/bin/env python 
# -*- coding:utf8 -*-
# from django.middleware.common import CommonMiddleware
from django.utils.deprecation import MiddlewareMixin

class M1(MiddlewareMixin):
    def process_request(self,request):
        print("m1.process_request")

    def process_view(self,request,callback,callback_args,callback_kwargs):
        print("m1.process_view")


    def process_response(self,request,response):
        print("m1.process_request")
        return response

class M2(MiddlewareMixin):
    def process_request(self,request):
        print("m2.process_request")

    def process_view(self, request, callback, callback_args, callback_kwargs):
        # print("m2.process_view")
        response = callback(request,*callback_args,**callback_kwargs)
        return response
    def process_response(self,request,response):
        print("m2.process_response")
        return response

3.1 views.py 抓取异常

#!/usr/bin/env python
# -*- coding:utf8 -*-
# from django.middleware.common import CommonMiddleware
from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import HttpResponse


class M1(MiddlewareMixin):
    def process_request(self, request):
        print("m1.process_request")

    def process_view(self, request, callback, callback_args, callback_kwargs):
        print("m1.process_view")

    def process_response(self, request, response):
        print("m1.process_request")
        return response

    def process_exception(self, request, exception):
        print("m1.process_exception")

class M2(MiddlewareMixin):
    def process_request(self,request):
        print("m2.process_request")
    def process_view(self,request,callback,callback_args,callback_kwargs):
        print("m2.process_view")
        # response = callback(request,*callback_args,**callback_kwargs)
        # return response
    def process_response(self,request,response):
        print("m2.process_response")
        return response
    def process_exception(self,request,exception):
        print("m2.process_exception")
        return HttpResponse('错拉...')

3.1.1

from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import HttpResponse
class M1(MiddlewareMixin):
    def process_request(self,request):
        print('m1.process_request')

    def process_view(self, request, callback, callback_args, callback_kwargs):
        print('m1.process_view')
        # response = callback(request,*callback_args,**callback_kwargs)
        # return response

    def process_response(self,request,response):
        print('m1.process_response')
        return response

    def process_exception(self, request, exception):
        print('m1.process_exception')

    def process_template_response(self,request,response):
        """
        视图函数的返回值中，如果有render方法，才被调用
        :param request:
        :param response:
        :return:
        """
        print('m1.process_template_response')
        return response

class M2(MiddlewareMixin):
    def process_request(self,request):
        print('m2.process_request')
    def process_view(self, request, callback, callback_args, callback_kwargs):
        print('m2.process_view')
    def process_response(self,request,response):
        print('m2.process_response')
        return response
    def process_exception(self, request, exception):
        print('m2.process_exception')
        return HttpResponse('错误了...')