Java：关闭选项卡或浏览器时为什么不会销毁http会话？ [英] Java:Why http session is not destroyed when tab or browser is closed?
问题描述
我有以下HttpSessionlistener实现
I have the following implementation of HttpSessionlistener
public class SessionListener implements HttpSessionAttributeListener, HttpSessionListener {
public void attributeAdded(HttpSessionBindingEvent event) {
...
}
public void attributeRemoved(HttpSessionBindingEvent event) {
...
}
public void attributeReplaced(HttpSessionBindingEvent event) {
}
//HttpSesion creation & destruction
public void sessionCreated(HttpSessionEvent event) {
HttpSession session = event.getSession();
//log created time
}
public void sessionDestroyed(HttpSessionEvent event) {
HttpSession session = event.getSession();
long destroyedTime = System.currentTimeMillis();
//log destroyed time
}
}
基本上我记录会话创建和销毁时间。
但是如果会话很长（默认为30分钟），并且用户同时关闭浏览器，那么</ p>
Basically i log the session creation and destruction time. But if the session is long (default to 30 minutes), and user closes browser meanwhile, the
sessionDestroyed
未被调用？
为什么？
是否有解决方法来准确记录会话被销毁的时间（当用户关闭浏览器时）？难道这不应该是浏览器的问题，在关闭会话时终止会话吗？
Why is that ? Is there a workaround to log exactly the when the session was destroyed (when user closes the browser)? Should'nt be this be the browser's problem, to kill the session when it is closed ?
我必须实现任何接口才能实现吗？
Is there any interface that i have to implement for this to work ?
谢谢！
推荐答案
服务器如何知道浏览器是什么时候关闭或标签关闭？此时浏览器不会向服务器发送任何内容。
How would the server know when the browser is closed or the tab closed? At that point the browser doesn't send anything to the server.
这是HTTP的基本部分 - 它是请求/响应协议，而不是永久打开的对话 你可以判断一方是否离开了对话。把它想象成一系列电报而不是电话 - 当你收到最后一封电报时，你无法分辨。
This is a fundamental part of HTTP - it's a request/response protocol, not a "permanently open conversation" where you can tell if one party leaves the conversation. Think of it as a series of telegrams rather than a phone call - and you can't tell when you've received the last telegram you're going to get.
您需要设计自己的方式 - 避免需要知道浏览器何时关闭。有一些丑陋的黑客可以解决它 - 例如，让AJAX用心跳信息对服务器进行轮询 - 但更改设计是一个更好的解决方案。
You'll need to design your way round this - to avoid needing to know when the browser has been closed. There are some ugly hacks to work around it - making AJAX poll the server with a heartbeat message, for example - but changing the design is a better solution.
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