booktest30-中间件2

1.在app目录下的middleware.py里面增加中间件类

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


# 中间件类
class BlockedIPSMiddleware(MiddlewareMixin):
    EXCLUDE_IPS = ['127.0.0.1']

    # 中间件函数
    def process_view(self, request, view_func, *view_args, **view_kwargs):
        '''视图函数调用之前调用这个'''
        userIp = request.META['REMOTE_ADDR']
        print(userIp)
        # 禁止某些IP访问
        if userIp in BlockedIPSMiddleware.EXCLUDE_IPS:
            return HttpResponse("
Forbidden
")


class TestMiddleware(MiddlewareMixin):
    def __init__(self,get_response=None):
        self.get_response = get_response
        print("init")

    def process_request(self,request):
        '''产生request对象之后，url匹配之前调用'''
        print('process_request')


    def process_view(self,request,view_func,*view_args,**view_kwargs):
        '''url匹配之后，视图函数调用之前'''
        print("process_view")

    def process_response(self,request,response):
        '''调用视图函数之后，内容返回之前'''
        print('process_response')
        return response


class ExceptionTestMiddleware(MiddlewareMixin):
    def process_exception(self,request,exception):
        '''视图函数发生异常时调用'''
        print('process_exception1')

class ExceptionTest2Middleware(MiddlewareMixin):
    def process_exception(self, request, exception):
        '''视图函数发生异常时调用'''
        print('process_exception2')

2.注销掉BlockedIPSMiddleware，添加注册新的中间件

 # 'booktest.middleware.BlockedIPSMiddleware',#注册中间件类
    'booktest.middleware.TestMiddleware',#注册中间件类
    'booktest.middleware.ExceptionTestMiddleware',#注册中间件类
    'booktest.middleware.ExceptionTest2Middleware',#注册中间件类

 3.访问http://127.0.0.1:8000/test_middleware两次，显示信息如下，init只在启动服务器后第一次访问时会执行

4.修改中间件方法process_request，返回HttpResponse,则会产生熔断，显示的信息如下

 def process_request(self,request):
        '''产生request对象之后，url匹配之前调用'''
        print('process_request')
        return HttpResponse('process_request')

5.在test_middleware视图函数中增加下面的代码，测试错误

num='a'+1