深入探究Django中的Session与Cookie_Python

前言

Cookie和Session相信对大家来说并不陌生，简单来说，Cookie和Session都是为了记录用户相关信息的方式，最大的区别就是Cookie在客户端记录而Session在服务端记录内容。

那么Cookie和Session之间的联系是怎么建立的呢？换言之，当服务器接收到一个请求时候，根据什么来判断读取哪个Session的呢？

对于Django默认情况来说，当用户登录后就可以发现Cookie里有一个sessionid的字段，根据这个key就可以取得在服务器端记录的详细内容。如果将这个字段删除，刷新页面就会发现变成未登录状态了。

对于Session的处理主要在源码django/contrib/sessions/middleware.py中，如下所示：

									import time

									from importlib import import_module

									from django.conf import settings

									from django.contrib.sessions.backends.base import UpdateError

									from django.core.exceptions import SuspiciousOperation

									from django.utils.cache import patch_vary_headers

									from django.utils.deprecation import MiddlewareMixin

									from django.utils.http import cookie_date

									class SessionMiddleware(MiddlewareMixin):

									 def __init__(self, get_response=None):

									  self.get_response = get_response

									  engine = import_module(settings.SESSION_ENGINE)

									  self.SessionStore = engine.SessionStore

									 def process_request(self, request):

									  session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)

									  request.session = self.SessionStore(session_key)

									 def process_response(self, request, response):

									  """

									  If request.session was modified, or if the configuration is to save the

									  session every time, save the changes and set a session cookie or delete

									  the session cookie if the session has been emptied.

									  """

									  try:

									   accessed = request.session.accessed

									   modified = request.session.modified

									   empty = request.session.is_empty()

									  except AttributeError:

									   pass

									  else:

									   # First check if we need to delete this cookie.

									   # The session should be deleted only if the session is entirely empty

									   if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:

									    response.delete_cookie(

									     settings.SESSION_COOKIE_NAME,

									     path=settings.SESSION_COOKIE_PATH,

									     domain=settings.SESSION_COOKIE_DOMAIN,

									    )

									   else:

									    if accessed:

									     patch_vary_headers(response, ('Cookie',))

									    if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:

									     if request.session.get_expire_at_browser_close():

									      max_age = None

									      expires = None

									     else:

									      max_age = request.session.get_expiry_age()

									      expires_time = time.time() + max_age

									      expires = cookie_date(expires_time)

									     # Save the session data and refresh the client cookie.

									     # Skip session save for 500 responses, refs #3881.

									     if response.status_code != 500:

									      try:

									       request.session.save()

									      except UpdateError:

									       raise SuspiciousOperation(

									        "The request's session was deleted before the "

									        "request completed. The user may have logged "

									        "out in a concurrent request, for example."

									       )

									      response.set_cookie(

									       settings.SESSION_COOKIE_NAME,

									       request.session.session_key, max_age=max_age,

									       expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,

									       path=settings.SESSION_COOKIE_PATH,

									       secure=settings.SESSION_COOKIE_SECURE or None,

									       httponly=settings.SESSION_COOKIE_HTTPONLY or None,

									      )

									  return response

当接收到一个请求时候，先在Cookie里取出key，然后根据key创建Session对象，在response时候判断是否要删除或者修改sessionid。

也就是说，Django中如果客户把浏览器Cookie禁用后，用户相关的功能就全都失效了，因为服务端根本没法知道当前用户是谁。

对于这种情况，关键点就是如何把sessionid不使用Cookie传递给客户端，常见的比如放在URL中，也就是URL重写技术。想实现这点可以自己写Middleware。不过django并不建议这么做：

The Django sessions framework is entirely, and solely, cookie-based. It does not fall back to putting session IDs in URLs as a last resort, as PHP does. This is an intentional design decision. Not only does that behavior make URLs ugly, it makes your site vulnerable to session-ID theft via the “Referer” header.

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对服务器之家的支持

原文链接：http://www.hi-roy.com/2017/07/28/django中的Session和Cookie/

深入探究Django中的Session与Cookie

相关文章

热门资讯