Java:为什么在关闭选项卡或浏览器时不会破坏 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 的实现
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，
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
不叫?
这是为什么?是否有一种解决方法可以准确记录会话被销毁的时间(当用户关闭浏览器时)?这不应该是浏览器的问题，在会话关闭时终止会话吗?
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 ?
有没有我必须实现的接口才能工作?
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何时关闭或选项卡何时关闭?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 - 它是一种请求/响应协议，而不是永久开放的对话"，您可以在其中判断一方是否离开对话.把它想象成一系列电报而不是一个电话——你不知道你什么时候收到了你将要收到的最后一份电报.
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.有一些丑陋的技巧可以解决这个问题——例如，让 AJAX 使用心跳消息轮询服务器——但改变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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