中间件

#0 GitHub

https://github.com/Coxhuang/django-Middleware

#1 环境

python3.6
Django==2.0.7

#2 中间件介绍

#2.1 定义

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。

#2.2 种类

process_request

process_view

process_exception

process_response

#3 概述

#3.1 配置

settings.py

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',
    'app.middleware.myMiddleware', # 自定义中间件的文件路径
]

app/middleware.py

from django.utils.deprecation import MiddlewareMixin
import datetime

class myMiddleware(MiddlewareMixin): # 继承Middlewaremixin

    def process_request(self, request):
        print("This is process_request : ",datetime.datetime.now())

        return None

    def process_response(self, request, response):
        print("This is process_request : ",datetime.datetime.now())

        return response # 必须要有

    def process_view(self, request, callback, callback_args, callback_kwargs):

        print("This is process_view : ", datetime.datetime.now())

    def process_exception(self, request, exception):

        print("This is process_exception : ", datetime.datetime.now())
        

#4 开始

#4.1 process_request / process_response

当用户发起请求的时候会依次经过所有的的中间件，这个时候的请求时process_request,最后到达views的函数中，views函数处理后，在依次穿过中间件，这个时候是process_response,最后返回给请求者,在django中叫中间件，在其他web框架中，有的叫管道，httphandle

#4.2 process_view

from django.utils.deprecation import MiddlewareMixin
import datetime

class myMiddleware(MiddlewareMixin):

    def process_view(self, request, callback, callback_args, callback_kwargs):

        print("This is process_view : ", datetime.datetime.now())

#4.3 process_exception

视图抛出异常后,才会进入异常的中间件函数