django-中间件

1.django中间件的5个方法

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HttpResponse对象和None值，如果是None则按照规则继续执行，如果为HttpResponse对象则直接将对象返回

2.django中间件的执行流程

（1）首先执行process_request函数，中间如果出现异常，则跳转到当前中间件的response函数中执行并返回。
（2）如果process_request执行结束，则会执行process_view函数，view的功能是与处理函数view执行了一次路由映射
（3）通过response返回给客户端
（4）process_exception是进行异常捕捉，如果视图函数view中运行错误，则调用此函数进行捕捉
（5）运行视图函数时，会进行异常捕捉，没有捕捉到异常则报错，捕捉到异常则会进行跳转最底层的response中返回
（6）process_template_response(self,request,response)->了解一下即可

3.自定义中间件

创建目录Middle，创建middleware.py文件

from django.utils.deprecation import MiddlewareMinin

class row1(MiddlewareMinin):
    def process_request(self,request):
        print("request-1")
    def process_response(self,request,response):
        print("response-1)"
        return response
     def process_view(self, request, callback, callback_args, callback_kwargs):
        print("view-1")
    
class row2(MiddlewareMinin):
    def process_request(self,request):
        print("request-2")
    def process_response(self,request,response):
        print("response-2)"
        return response    
     def process_view(self, request, callback, callback_args, callback_kwargs):
        print("view-2")

class row3(MiddlewareMinin):
    def process_request(self,request):
        print("request-3")
    def process_response(self,request,response):
        print("response-3)"
        return response
     def process_view(self, request, callback, callback_args, callback_kwargs):
        print("view-3")

4.中间件注册

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',
    'Middle.middleware.Row1',#自定义中间的注册
    'Middle.middleware.Row2',
    'Middle.middleware.Row3',
]

注意，中间件的执行顺序按照配置自上向下