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Django 中间件

一、Django 中间件基础

1.1 中间件工作原理

中间件是 Django 请求/响应处理的钩子框架。它是一个轻量级 的、底层的插件系统，用于全局修改 Django的输入或输出。每个中间件组件负责执行某些特定的功能。

1.2 中间件方法

class MiddlewareMixin:def __init__(self, get_response=None):self.get_response = get_responsedef __call__(self, request):response = Noneif hasattr(self, 'process_request'):response = self.process_request(request)response = response or self.get_response(request)if hasattr(self, 'process_response'):response = self.process_response(request, response)return response

中间件类可以实现以下方法：

• process_request(request)
• process_view(request, view_func, view_args, view_kwargs)
• process_template_response(request, response)
• process_exception(request, exception)
• process_response(request, response)

二、自定义中间件示例

2.1 请求时间统计中间件

# middleware/timing.py
import time
from django.utils.deprecation import MiddlewareMixin
from django.core.cache import cacheclass RequestTimingMiddleware(MiddlewareMixin):def process_request(self, request):request.start_time = time.time()def process_response(self, request, response):if hasattr(request, 'start_time'):total_time = time.time() - request.start_timeresponse['X-Request-Time'] = f'{total_time:.2f}s'# 记录慢请求if total_time > 1.0:  # 超过1秒的请求cache.set(f'slow_request_{request.path}_{time.time()}',{'path': request.path,'method': request.method,'time': total_time,'user': str(request.user),},timeout=86400  # 24小时过期)return response

2.2 IP访问限制中间件

# middleware/ip_restriction.py
from django.core.exceptions import PermissionDenied
from django.core.cache import cache
from django.conf import settingsclass IPRestrictionMiddleware:def __init__(self, get_response):self.get_response = get_response# 白名单IP列表self.allowed_ips = getattr(settings, 'ALLOWED_IPS', [])def __call__(self, request):ip = self.get_client_ip(request)# 检查IP访问频率if self.is_ip_banned(ip):raise PermissionDenied('访问频率过高，请稍后再试')# 记录IP访问次数self.record_ip_request(ip)response = self.get_response(request)return responsedef get_client_ip(self, request):x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')if x_forwarded_for:ip = x_forwarded_for.split(',')[0]else:ip = request.META.get('REMOTE_ADDR')return ipdef is_ip_banned(self, ip):if ip in self.allowed_ips:return False# 获取IP的访问次数key = f'ip_requests_{ip}'requests = cache.get(key, 0)# 如果1分钟内访问超过100次，则禁止访问return requests > 100def record_ip_request(self, ip):key = f'ip_requests_{ip}'timeout = 60  # 1分钟过期# 原子操作增加计数cache.add(key, 0, timeout)cache.incr(key)

2.3 用户行为日志中间件

# middleware/user_logging.py
import json
import logging
from django.utils.deprecation import MiddlewareMixinlogger = logging.getLogger('user_behavior')class UserBehaviorMiddleware(MiddlewareMixin):def process_request(self, request):request.behavior_log = {'path': request.path,'method': request.method,'user_agent': request.META.get('HTTP_USER_AGENT', ''),'ip': self.get_client_ip(request),'user': str(request.user),'data': {}}# 记录请求数据if request.method in ['POST', 'PUT', 'PATCH']:try:request.behavior_log['data']['body'] = json.loads(request.body)except:request.behavior_log['data']['body'] = str(request.POST)if request.method == 'GET':request.behavior_log['data']['query'] = dict(request.GET)def process_response(self, request, response):if hasattr(request, 'behavior_log'):# 添加响应状态码request.behavior_log['status_code'] = response.status_code# 记录日志logger.info('User Behavior',extra={'behavior': request.behavior_log})return responsedef get_client_ip(self, request):x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')if x_forwarded_for:ip = x_forwarded_for.split(',')[0]else:ip = request.META.get('REMOTE_ADDR')return ip

三、中间件配置与使用

# settings.py
MIDDLEWARE = [# 提供了一系列的安全功能，如通过设置 X-Content-Type-Options 和 X-XSS-Protection 等 HTTP 头来增强安全性。'django.middleware.security.SecurityMiddleware',# 用于管理会话（Sessions）。它负责在用户浏览网站时，在服务器和客户端之间保持状态。'django.contrib.sessions.middleware.SessionMiddleware',# 提供了一些常用功能，例如将请求对象中的 request.user 和 request.path 等属性设置为当前用户和请求的路径。'django.middleware.common.CommonMiddleware',# 用于防止跨站请求伪造（CSRF）。它检查 POST 请求中的 CSRF token，确保请求是由当前用户发出的。'django.middleware.csrf.CsrfViewMiddleware',# 用于处理用户认证。它检查每个请求，看是否有用户已通过认证，并将用户对象存储在请求对象中，以便于后续的视图函数使用。'django.contrib.auth.middleware.AuthenticationMiddleware',# 用于处理消息传递。它允许你在模板中显示消息（例如表单错误或成功消息）。'django.contrib.messages.middleware.MessageMiddleware',# 防止点击劫持攻击。它通过设置 HTTP 响应头 X-Frame-Options 来防止网页被嵌入到其他网站中。'django.middleware.clickjacking.XFrameOptionsMiddleware',# 自定义中间件'middleware.timing.RequestTimingMiddleware','middleware.ip_restriction.IPRestrictionMiddleware','middleware.user_logging.UserBehaviorMiddleware',
]

请求进来时，中间件的执行顺序由上往下，响应返回时，由下往上