Twisted系列web编程之六 :SESSION 的处理

前面讲到了利用twisted来动态生成网页，动态dispatch url, 处理get 请求，处理post请求的数据，但还有一个重要的东西。在做网页开发时必不可少，就是 session 管理。怎么得到session, 怎么测底销毁一个session,怎么在session 中存入数据，怎么设置 session 的过期时间。这是要解决的问题。
一, Session 的创建与销毁.

from twisted.internet import reactor
from twisted.web.resource import Resource
from twisted.web.server import Site

class ShowSession(Resource):
    def render_GET(self, request):
        return 'Your session id is: ' + request.getSession().uid

class ExpireSession(Resource):
    def render_GET(self, request):
        request.getSession().expire()
        return 'Your session has been expired.'

resource = ShowSession()
resource.putChild("expire", ExpireSession())
resource.putChild('getsession',ShowSession())

factory = Site(resource)
reactor.listenTCP(8880, factory)
reactor.run()  

运行程序，并在浏览器地址栏输入 http://localhost:8880/getsession, 会得到session id, 如果在浏览器输入 http://localhost:8880/expire ,会销毁session

二 在 session 中保存内容，比如保存一个计数器，每次访问就加一。

from twisted.internet import reactor
from twisted.python.components import registerAdapter
from twisted.web.resource import Resource
from twisted.web.server import Session, Site
from zope.interface import Interface, Attribute, implements

class ICounter(Interface):
    value = Attribute("An int value which counts up once per page view.")

class Counter(object):
    implements(ICounter)
    def __init__(self, session):
        self.value = 0

registerAdapter(Counter, Session, ICounter)

class CounterResource(Resource):
    def render_GET(self, request):
        session = request.getSession()
        counter = ICounter(session)   
        counter.value += 1
        return "Visit #%d for you!" % (counter.value,)

resource = CounterResource()
resource.putChild("count", CounterResource())
factory = Site(resource)
reactor.listenTCP(8880, factory)
reactor.run() 

运行程序之后，在浏览器上输入 http://locaohost:8880/count 会发现计数器变化，每次刷新网页，计数器将会加一.

三。设置 session 的过期时间。

from twisted.web.server import Site, Session
from twisted.web.resource import Resource
from twisted.internet import reactor

class ShortSession(Session):
    sessionTimeout = 5

class ExpirationLogger(Resource):
    sessions = set()

    def render_GET(self, request):
        session = request.getSession()
        if session.uid not in self.sessions:
            self.sessions.add(session.uid)
            session.notifyOnExpire(lambda: self._expired(session.uid))
        return ""

    def _expired(self, uid):
        print "Session", uid, "has expired."
        self.sessions.remove(uid)

rootResource = Resource()
rootResource.putChild("logme", ExpirationLogger())
factory = Site(rootResource)
factory.sessionFactory = ShortSession

reactor.listenTCP(8880, factory)
reactor.run()

运行程序，在浏览器上输入 http://localhost:8880/logme 可以发现session 销毁，另外，等5秒钟，session 也会超时销毁.

From：一号门