如何检查所有用户登录到我的应用程序 [英] How can i check which all users are logged into my application

问题描述

我有一个基于网络的应用程序，它使用userName和密码进行登录。

I have a web based application that uses userName and password for login.

现在如何检查所有用户在该时间登录的特定时间。
i我正在使用会话管理，并且在应用程序中没有使用数据库，一切都在文件系统上

now how can i check on certain time which all users are logged in at that very time. i am using session management and no DB is used in application everything is on filesystem

编辑：1更傻的怀疑..如何定义应用范围的变量..这是这种东西吗？

1 more silly doubt.. how to define a variable with application scope.. is this something of this sort?

<env-entry>
<env-entry-name>test/MyEnv2</env-entry-name>
<env-entry-type>java.lang.Boolean</env-entry-type>
<env-entry-value>true</env-entry-value>
</env-entry>

推荐答案

只需收集<$ c中的所有登录用户$ c>在应用程序范围内设置。如果你的应用程序设计得很好，你应该有一个javabean User 代表登录用户。让它实现 HttpSessionBindingListener 并在 Set 中添加/删除用户在会话中即将绑定/未绑定时。

Just collect all logged in users in a Set in the application scope. If your application is well designed, you should have a javabean User which represents the logged-in user. Let it implement HttpSessionBindingListener and add/remove the user from the Set when it's about to be bound/unbound in the session.

Kickoff示例：

Kickoff example:

public class User implements HttpSessionBindingListener {

    @Override
    public void valueBound(HttpSessionBindingEvent event) {
        Set<User> logins = (Set<User>) event.getSession().getServletContext().getAttribute("logins");
        logins.add(this);
    }

    @Override
    public void valueUnbound(HttpSessionBindingEvent event) {
        Set<User> logins = (Set<User>) event.getSession().getServletContext().getAttribute("logins");
        logins.remove(this);
    }

    // @Override equals() and hashCode() as well!

}

请注意，您需要准备在应用程序范围中设置，使其在上述方法中不返回 null 。您可以通过nullcheck在相同的方法中执行此操作，或者在 ServletContextListener＃contextInitialized（） 。

Note that you need to prepare the Set in the application scope so that it doesn't return null in above methods. You could do that in the same methods by a nullcheck, or with help of ServletContextListener#contextInitialized().

然后，在您的应用程序中您可以访问 ServletContext 的任何地方，就像在servlet中一样，您可以按如下方式访问已登录的用户：

Then, anywhere in your application where you've access to the ServletContext, like in a servlet, you can just access the logged-in users as follows:

Set<User> logins = (Set<User>) getServletContext().getAttribute("logins");

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