如何在java中检查会话是否已过期？
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how to check session has been expired in java?
提问by user241924
Is there any other way to check expiry of session other than this
除了这个，还有没有其他方法可以检查会话的到期时间
session.isNew()
session.isNew()
回答by Carl Smotricz
Yes:
是的：
you can call
HttpServletRequest.getSession(false)and you'll get anullinstead of a session if there isn't one active already.you can define a lifecycle listener (using
HttpSessionListener) in yourweb.xml. That way you can get notified the moment a session bites the dust.
你可以打电话
HttpServletRequest.getSession(false)，null如果还没有活动的话，你会得到一个而不是一个会话。您可以
HttpSessionListener在web.xml. 这样您就可以在会话尘埃落定的那一刻得到通知。
回答by Danilo Piazzalunga
With session.isNewyou can not distinguish expired sessions from entirely new sessions.
You can check if the session has expired and/or timed out with:
随着session.isNew你无法区分全新的会话过期会话。您可以检查会话是否已过期和/或超时：
if (request.getRequestedSessionId() != null
&& !request.isRequestedSessionIdValid()) {
// Session is expired
}
Use getRequestedSessionIdto distinguish between new and existing (valid/expired) sessions, and use isRequestedSessionIdValidto distinguish betwheen valid and new/expired sessions.
使用getRequestedSessionId新的和现有的（有效/过期）的会话，并使用区分isRequestedSessionIdValid区分betwheen有效的和新的/过期的会话。
You can put this code in a Filter.
您可以将此代码放在Filter 中。
