Django middleware中间件

待我称王封你为后i 2023-07-10 11:13 18阅读 0赞

**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][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4OTAwNTY1_size_16_color_FFFFFF_t_70]  
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

从console输出可知，顺序执行，并且两次进过middleware

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4OTAwNTY1_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200301232133629.PNG?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4OTAwNTY1,size_16,color_FFFFFF,t_70