Django补充——中间件、请求的生命周期等

一：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、创建中间件类

class RequestExeute(object): def process_request(self,request): pass def process_view(self, request, callback, callback_args, callback_kwargs): i =1 pass def process_exception(self, request, exception): pass def process_response(self, request, response): return response """ class M1(MiddlewareMixin): def process_request(self,request): print('m1.process_request') def process_view(self,request, view_func, view_func_args, view_func_kwargs): print('m1.process_view') def process_exception(self,request,exception): print('m1.process_exception') def process_response(self,request,response): print('m1.process_response') return response def process_template_response(self,request,response): print('m1.process_template_response') return response class M2(MiddlewareMixin): def process_request(self, request): print('m2.process_request') def process_view(self, request, view_func, view_func_args, view_func_kwargs): print('M2.process_view') def process_exception(self,request,exception): print('m2.process_exception') return HttpResponse('开发的程序员已经被打死') def process_response(self, request, response): print('m2.process_response') return response def process_template_response(self,request,response): print('m2.process_template_response') return response """ from django.shortcuts import HttpResponse,redirect class MiddlewareMixin(object): def __init__(self, get_response=None): self.get_response = get_response super(MiddlewareMixin, self).__init__() def __call__(self, request): response = None if hasattr(self, 'process_request'): response = self.process_request(request) if not response: response = self.get_response(request) if hasattr(self, 'process_response'): response = self.process_response(request, response) return response class M1(MiddlewareMixin): def process_response(self, request, response): print('m2.process_response') return response class M2(MiddlewareMixin): def process_request(self, request): print('m2.process_request') 两种方式

2、注册中间件

MIDDLEWARE_CLASSES = ( 'django.contrib.sessions.middleware.SessionMiddleware', 'django.middleware.common.CommonMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.auth.middleware.SessionAuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', 'django.middleware.clickjacking.XFrameOptionsMiddleware', 'wupeiqi.middleware.auth.RequestExeute', #在合适的位置引入 　 'md.middleware.M1', 　 'md.middleware.M2', )

二、 Http请求本质

　　Django程序：socket服务端

　　　　a. 服务端监听IP和端口　　　　c. 接受请求　　　　　　\r\n\r\n：请求头和请求体　　　　　　\r\n　　　　　　&　　　　　　request.POST　　　　　　request.GET　　　　d. 响应：　　　　　　响应头： location：www.oldboyedu.com　　　　　　响应体　　　　e. 断开连接

　　浏览器： socket客户端

　　　　b. 浏览器发送：　　　　　　GET请求：　　　　　　　　"GET /index.html http1.1\r\nUser-Agent:Mozilla/5.0 (Windows NT 6.1; Win64; x6..\r\n\r\nAccept-Encoding:gzip\r\n\r\n"　　　　　　POST请求：　　　　　　　　"POST /index.html http1.1\r\nUser-Agent:Mozilla/5.0 (Windows NT 6.1; Win64; x6..\r\n\r\nAccept-Encoding:gzip\r\n\r\nuser=cqz&hobby=lihao"　　　　e. 断开连接　　COOKIE: 请求头和响应头中存在

三、Django请求的生命周期

wsgi    -> 中间件     -> 路由系统     -> 视图函数（ORM，Template，渲染）　　- wsgiref　　- uwsgi

四、FBV和CBV

1、FBV

FBV（function base views） 就是在视图里使用函数处理请求。

看代码：

urls.py

from django.conf.urls import url, include # from django.contrib import admin from mytest import views urlpatterns = [ # url(r‘^admin/‘, admin.site.urls), url(r‘^index/‘, views.index), ]

views.py

from django.shortcuts import render def index(req): if req.method == ‘POST‘: print(‘method is :‘ + req.method) elif req.method == ‘GET‘: print(‘method is :‘ + req.method) return render(req, ‘index.html‘)

注意此处定义的是函数【def index(req):】

index.html

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>index</title> </head> <body> <form action="" method="post"> <input type="text" name="A" /> <input type="submit" name="b" value="提交" /> </form> </body> </html>

2、CBV

CBV（class base views） 就是在视图里使用类处理请求。

将上述代码中的urls.py 修改为如下：

from mytest import views urlpatterns = [ # url(r‘^index/‘, views.index), url(r‘^index/‘, views.Index.as_view()), ]

注：url(r‘^index/‘, views.Index.as_view()),  是固定用法。

将上述代码中的views.py 修改为如下：

from django.views import View class Index(View): def get(self, req): print(‘method is :‘ + req.method) return render(req, ‘index.html‘) def post(self, req): print(‘method is :‘ + req.method) return render(req, ‘index.html‘)

3、装饰器的使用

from django.utils.decorators import method_decorator

3.1 在get，post方法上

class LoginView(View): def dispatch(self, request, *args, **kwargs): return super(LoginView,self).dispatch(request, *args, **kwargs) def get(self,request): return render(request,'login.html') @method_decorator(test) def post(self,request): # request.GET # request.POST # 请求头中的：content-type # request.body user = request.POST.get('user') pwd = request.POST.get('pwd') if user == 'alex' and pwd == "alex3714": # 生成随机字符串 # 写浏览器cookie： session_id: 随机字符串 # 写到服务端session： # { # "随机字符串": {'user_info':'alex} # } request.session['user_info'] = "alex" return redirect('/index.html') return render(request, 'login.html')

3.2 在dispatch方法上

class LoginView(View): @method_decorator(test) def dispatch(self, request, *args, **kwargs): return super(LoginView,self).dispatch(request, *args, **kwargs) def get(self,request): return render(request,'login.html') def post(self,request): # request.GET # request.POST # 请求头中的：content-type # request.body user = request.POST.get('user') pwd = request.POST.get('pwd') if user == 'alex' and pwd == "alex3714": # 生成随机字符串 # 写浏览器cookie： session_id: 随机字符串 # 写到服务端session： # { # "随机字符串": {'user_info':'alex} # } request.session['user_info'] = "alex" return redirect('/index.html') return render(request, 'login.html') View Code

3.3 在类上

@method_decorator(test,name='get') class LoginView(View): def dispatch(self, request, *args, **kwargs): return super(LoginView,self).dispatch(request, *args, **kwargs) def get(self,request): return render(request,'login.html') def post(self,request): # request.GET # request.POST # 请求头中的：content-type # request.body user = request.POST.get('user') pwd = request.POST.get('pwd') if user == 'alex' and pwd == "alex3714": # 生成随机字符串 # 写浏览器cookie： session_id: 随机字符串 # 写到服务端session： # { # "随机字符串": {'user_info':'alex} # } request.session['user_info'] = "alex" return redirect('/index.html') return render(request, 'login.html')

特殊：CSRF Token只能加到dispatch

from django.views.decorators.csrf import csrf_exempt,csrf_protect class LoginView(View): @method_decorator(csrf_exempt) def dispatch(self, request, *args, **kwargs): return super(LoginView,self).dispatch(request, *args, **kwargs) def get(self,request): return render(request,'login.html') def post(self,request): # request.GET # request.POST # 请求头中的：content-type # request.body user = request.POST.get('user') pwd = request.POST.get('pwd') if user == 'alex' and pwd == "alex3714": # 生成随机字符串 # 写浏览器cookie： session_id: 随机字符串 # 写到服务端session： # { # "随机字符串": {'user_info':'alex} # } request.session['user_info'] = "alex" return redirect('/index.html') return render(request, 'login.html') View Code

 

转载于:https://www.cnblogs.com/Vee-Wang/p/7553534.html