Django middleware中间件-蒲公英云

Django middleware中间件

1.什么是Django中间件
2.Django中间件的执行逻辑
3.实现自定义中间件

1.什么是DJango中间件
Django中间件是一个类；
请求前后在合适的时机执行相应的方法；
可以通过在settings文件中配置MIDDLEWARE_CLASSES属性来设置使用何种中间件。

MIDDLEWARE = [
    # 安全中间件，处理请求应答安全的处理
    'django.middleware.security.SecurityMiddleware',
    # 提供由状态服务Session中间件
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    # 防止跨站伪造请求的中间件
    # 'django.middleware.csrf.CsrfViewMiddleware',
    # Django自带的认证体系中间件
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    # 消息中间件
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

Gzip压缩中间件，处理网页请求/应答中文件压缩：GzipMiddleware

2.Django中间件执行逻辑
如下图，每个请求都会两次经过配置的中间件，多个中间件之间存在执行顺序。
在这里插入图片描述
3.实现自定义中间件
settings.py

# 项目启动后自动实例化所有中间件
MIDDLEWARE = [
    ...
    'ops.middlewaredemo.TestMiddleware',
    'ops.middlewaredemo.Test2Middleware',
    ...
]

ops/middlewaredemo.py

class TestMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response
        print('build TestMiddleware')
    def __call__(self, request):
        print('TestMiddleware before request.')
        response = self.get_reponse(request)
        print('TestMiddleware after request.')
        return response
class Test2Middleware:
    def __init__(self, get_response):
        self.get_response = get_response
        print('build TestMiddleware')
    def __call__(self, request):
        print('Test2 before request.')
        response = self.get_reponse(request)
        print('Test2 after request.')
        return response

apis/views/test.py

def helloworld(request):
    data = dict()
    data['query'] = request.GET.get('info')
    # http://127.0.0.1:8000/api/v1.0/service/hello?info=beijing
    return JsonResponse(data=data, safe=False, status=200)  # {"query": "beijing"}

配置路由后，启动项目访问web helloworld
console:

D:\django_project\backend_ch1_sec1\ops\middlewaredemo.py: __call__: 13 INFO - TestMiddleware before request.
D:\django_project\backend_ch1_sec1\ops\test2middleware.py: __call__: 14 INFO - Test2 before request.
D:\django_project\backend_ch1_sec1\ops\test2middleware.py: __call__: 16 INFO - Test2 after request.
D:\django_project\backend_ch1_sec1\ops\middlewaredemo.py: __call__: 16 INFO - TestMiddlerware after request.
E:\Python\lib\site-packages\django\core\servers\basehttp.py: log_message: 124 INFO - "GET /api/v1.0/service/hello?info=beijing HTTP/1.1" 200 20