查找从给定客户端 IP 创建的活动会话数 [英] Find number of active sessions created from a given client IP

问题描述

有没有办法确定从给定的客户端 IP 地址创建的活动会话的数量?

Is there a way to determine the number of active sessions created from a given client IP address?

推荐答案

标准的 Servlet API 没有为此提供工具.你能做的最好的事情就是维护一个 Map<HttpSession, String> 自己(其中 String 是 IP 地址)并检查每个 ServletRequest 如果 HttpSession#isNew() 并将其添加到 Map 以及 <代码>ServletRequest#getRemoteAddr().然后您可以使用 Collections#frequency() 在 Map#values().您只需要确保在 HttpSessionListener#sessionDestroyed().

The standard Servlet API doesn't offer facilities for that. Best what you can do is to maintain a Map<HttpSession, String> yourself (where the String is the IP address) with and check on every ServletRequest if the HttpSession#isNew() and add it to the Map along with ServletRequest#getRemoteAddr(). Then you can get the amount of IP addresses with an active session using Collections#frequency() on Map#values(). You only need to ensure that you remove the HttpSession from the Map during HttpSessionListener#sessionDestroyed().

这一切都可以在实现 Listener 中完成rel="noreferrer">ServletContextListener, HttpSessionListener 和 ServletRequestListener.

This all can be done in a single Listener implementing the ServletContextListener, HttpSessionListener and ServletRequestListener.

这是一个启动示例:

public class SessionCounter implements ServletContextListener, HttpSessionListener, ServletRequestListener {

    private static final String ATTRIBUTE_NAME = "com.example.SessionCounter";
    private Map<HttpSession, String> sessions = new ConcurrentHashMap<HttpSession, String>();

    @Override
    public void contextInitialized(ServletContextEvent event) {
        event.getServletContext().setAttribute(ATTRIBUTE_NAME, this);
    }

    @Override
    public void requestInitialized(ServletRequestEvent event) {
        HttpServletRequest request = (HttpServletRequest) event.getServletRequest();
        HttpSession session = request.getSession();
        if (session.isNew()) {
            sessions.put(session, request.getRemoteAddr());
        }
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent event) {
        sessions.remove(event.getSession());
    }

    @Override
    public void sessionCreated(HttpSessionEvent event) {
        // NOOP. Useless since we can't obtain IP here.
    }

    @Override
    public void requestDestroyed(ServletRequestEvent event) {
        // NOOP. No logic needed.
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        // NOOP. No logic needed. Maybe some future cleanup?
    }

    public static SessionCounter getInstance(ServletContext context) {
        return (SessionCounter) context.getAttribute(ATTRIBUTE_NAME);
    }

    public int getCount(String remoteAddr) {
        return Collections.frequency(sessions.values(), remoteAddr);
    }

}

在web.xml中定义如下:

<listener>
    <listener-class>com.example.SessionCounter</listener-class>
</listener>

您可以在任何 servlet 中使用它，如下所示:

You can use it in any servlet like follows:

SessionCounter counter = SessionCounter.getInstance(getServletContext());
int count = counter.getCount("127.0.0.1");

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