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This article is to share with you what are several methods of setting Session failure, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article. Let's take a look at it.

The Session object is an instance of HttpSessionState. This class provides information for the current user session, access to caches that can be used to store information session scope, and methods to control how the session is managed. Here are several ways to set up session failures.

After the system logs in, the current session expiration time is set to ensure that the user does not interact with the server for a long time, automatically log out and destroy the session.

The specific settings are simple, and there are three ways:

(1) add: session.setMaxInactiveInterval (900) to the main page or public page; the parameter 900U is seconds, that is, after 15 minutes of no activity, session will become invalid.

Note here that the time of this session setting is calculated based on the server, not the client. So if you are debugging a program, you should modify the server-side time to test, not the client.

(2) it is also a general method to set the failure time of session, that is, in the web.xml of the project.

one

(3) set it directly in the application server. If it is tomcat, you can find the element in conf/web.xml under the tomcat directory. The default setting of tomcat is 30 minutes. You only need to change this value.

It should be noted that if all three places are set, there is a priority problem, from high to low: (1) > (2) > (3)

In a general system, you may also need to do something after the session fails.

(1) Control the number of users, when the session fails, the number of users of the system will be reduced by one, and the number of users will be controlled within a certain range to ensure the performance of the system.

(2) Control a user to log in multiple times. When session is valid, if the same user logs in, it will prompt you to log in. When the session expires, you can log in directly without prompting.

So how to perform a series of operations after the failure of session?

The listener is needed here, that is, when the session fails for various reasons, the listener can listen and then execute the program defined in the listener.

The listener class is: HttpSessionListener class, with sessionCreated and sessionDestroyed methods

You can inherit this class and implement it separately.

SessionCreated refers to the method that is executed when the session is created

SessionDestroyed refers to the method performed when the session fails

Give a simple example:

Public class SessionListener implements HttpSessionListener {public void sessionCreated (HttpSessionEvent event) {HttpSession ses = event.getSession (); String id=ses.getId () + ses.getCreationTime (); SummerConstant.UserMap.put (id, Boolean.TRUE); / / add users} public void sessionDestroyed (HttpSessionEvent event) {HttpSession ses = event.getSession (); String id=ses.getId () + ses.getCreationTime (); synchronized (this) {SummerConstant.USERNUM--; / / number of users minus one SummerConstant.UserMap.remove (id) / / remove from the user group, which is a map}

Then you just need to declare the listener in web.xml.

Com.demo.SessionListener above are several ways to set Session failure. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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