中间件：

Django的请求的生命周期：

中间件

process_request(self,request)

参数：

request 请求的对象，和视图中的request是同一个

执行时间：视图函数之前

执行顺序：

按照注册的顺序 顺序执行

返回值

None ： 正常流程

HttpReponse: 当前中间件之后的中间件的process_request方法、路由匹配、视图也不执行，直接执行当前中间件的process_response方法

settings：

"""
Django settings for about_middleware project.

Generated by 'django-admin startproject' using Django 1.11.26.

For more information on this file, see
https://docs.djangoproject.com/en/1.11/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.11/ref/settings/
"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = '^t344mb401h!=^hd&igb4_-39*z$ldlb(0$4a==4r7lu+6)yb8'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'app01.apps.App01Config',
]

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',
    'app01.middlewares.my_middleware.MD1',  #注册中间件1
    'app01.middlewares.my_middleware.MD2',  #注册中间件2
]

ROOT_URLCONF = 'about_middleware.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join ( BASE_DIR, 'templates' )]
        ,
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'about_middleware.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.11/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/1.11/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.11/howto/static-files/

STATIC_URL = '/static/'
定义中间件my_middleware：

from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import HttpResponse

class MD1(MiddlewareMixin):
    def process_request(self,request):
        # print(id(request))
        # request.name = "alexdsb"
        print(" MD1 process_request ")
        return HttpResponse("md1 response")

class MD2(MiddlewareMixin):
    def process_request(self,request):
        print("MD2 process_request")

process_response(self, request, response)

参数：

request 请求的对象，和视图中的request是同一个

response 返回的响应对象

执行时间：视图函数之后

执行顺序：

按照注册的顺序 倒叙执行

返回值

HttpReponse: 必须返回响应对象

 

process_view(self, request, view_func, view_args, view_kwargs)

参数：

request 请求的对象，和视图中的request是同一个

view_func 视图函数

view_args 视图函数的位置参数

view_kwargs 视图函数的关键字参数

执行时间：路由匹配之后，视图函数之前

执行顺序：

按照注册的顺序 顺序执行

返回值

None 正常流程

HttpReponse: 当前中间件之后的process_view、视图不执行，执行最后一个中间的process_response

process_exception(self, request, exception)

参数：

request 请求的对象，和视图中的request是同一个

exception 错误对象

执行时间（触发条件）：视图层面有错误才执行

执行顺序：

按照注册的顺序 倒叙执行

返回值

None 当前中间没有处理异常，交由下一个中间件处理异常，所有的中间件都没有处理，Django处理错误

HttpReponse: 当前中间处理好异常，之后执行最后一个中间件的process_response方法

 

pocess_template_response(self,request,response)

参数：

request 请求的对象，和视图中的request是同一个

response 返回的响应对象

执行时间：视图必须返回一个template_response对象

执行顺序：

按照注册的顺序 倒叙执行

返回值

HttpReponse: 必须返回响应对象

 response.template_name = 'index1.html'  # 改模板
 response.context_data # 改变量