如何在嵌入式jetty服务器的应用程序中获取活动会话/上下文/用户？

Question

我有一个运行的jetty-server，具有基本的身份验证功能。现在我想在应用程序中看到哪些用户已登录并具有活动会话。我希望用户保存jpa数据库中的更改，因此我需要在我的JpaService类中获取信息以保存用户的更改。我正在运行的服务器是

public class TestServer {

public static void main(String[] args) {
    startServer();
}

public static void startServer() {
    Server server = new Server(8899);

    ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
    context.setContextPath("/");
    context.setSecurityHandler(basicAuth());                
    server.setHandler(context);

    ServletHolder jerseyServlet = context.addServlet(org.glassfish.jersey.servlet.ServletContainer.class, "/*");
    jerseyServlet.setInitOrder(0);
    jerseyServlet.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true");
    jerseyServlet.setInitParameter("jersey.config.server.provider.classnames", JpaService.class.getCanonicalName());

    try {
        server.start();
        server.join();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        server.destroy();
    }
}

private static final SecurityHandler basicAuth() {
    HashLoginService l = new HashLoginService();

    l.putUser("user1", Credential.getCredential("pass1"), new String[] {"user"});
    l.putUser("user2", Credential.getCredential("pass2"), new String[] { "admin"});
    l.setName("Private Server");

    Constraint constraint = new Constraint();
    constraint.setName(Constraint.__BASIC_AUTH);
    constraint.setRoles(new String[] { "admin", "user" });
    constraint.setAuthenticate(true);

    ConstraintMapping cm = new ConstraintMapping();
    cm.setConstraint(constraint);
    cm.setPathSpec("/*");

    ConstraintSecurityHandler csh = new ConstraintSecurityHandler();
    csh.setAuthenticator(new BasicAuthenticator());
    csh.setRealmName("NameOfRealm");
    csh.addConstraintMapping(cm);
    csh.setLoginService(l);

    return csh;
}

}

那么我如何“阅读”相关信息呢？我使用jetty 9.2.3而Get jetty realm credentials in application似乎过时了。

我尝试添加以下几种方法来添加以下内容，但没有任何反应。

public class HttpSessionCollector implements HttpSessionListener {
private static final Map<String, HttpSession> sessions = new HashMap<String, HttpSession>();

@Override
public void sessionCreated(HttpSessionEvent event) {
    HttpSession session = event.getSession();
    sessions.put(session.getId(), session);
    System.out.println("Created Session: "+event.getSession().getId());
    System.out.println("Last Accessed: "+new Date(event.getSession().getLastAccessedTime()));
    System.out.println("Attributes: "+ event.getSession().getAttributeNames());
}

@Override
public void sessionDestroyed(HttpSessionEvent event) {
    sessions.remove(event.getSession().getId());
    System.out.println("Destroyed Session: "+event.getSession().getId());
}

public static HttpSession find(String sessionId) {
    return sessions.get(sessionId);
}

public static Map<String, HttpSession> getSessions() {
    return sessions;
}
}

当我添加context.getSessionHandler().getState()时，它会显示“已停止”。当我尝试.start()时，我得到一个NullPointerException。也许我做错了，但它是如何完成的，所以我在我的网络应用程序中登录用户？