java HttpServletRequest.getSession(false)：什么时候返回null？
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HttpServletRequest.getSession(false): When does it return null?
提问by AndrewBourgeois
I'd like to know when to expect a "null" when calling HttpServletRequest.getSession(false)
我想知道在调用HttpServletRequest.getSession(false)时什么时候会出现“null”
Also: Are there good tutorials on HttpSession? I'd like to get details like: when to invalidate()? what are the consequences? do I need to check if the returned HttpSession is valid? ... <== Answer that in a comment please.
另外：有关于 HttpSession 的好教程吗？我想获得以下详细信息：何时失效（）？后果是什么？我是否需要检查返回的 HttpSession 是否有效？... <== 请在评论中回答。
采纳答案by 0xCAFEBABE
You should practically never expect a null value. As the documentation says, if there is no active session for a request (usually, you would check for that in the filter chain of a request), a session will be created. If you get a null value from this, I'd wager that there is a problem in the underlying OS: Not enough memory to spawn a session would come to mind.
您几乎不应该期望空值。正如文档所说，如果请求没有活动会话（通常，您会在请求的过滤器链中检查它），将创建一个会话。如果你从中得到一个空值，我敢打赌底层操作系统存在问题：没有足够的内存来产生一个会话。
