请教一个关于jsp在线人数统计的问题

//User类
public class User implements HttpSessionBindingListener
{
    private String name;

    public int count = 0;

    public User()
    {
    }

    public User(String name)
    {
        this.name = name;
    }

    public void valueBound(HttpSessionBindingEvent arg0)
    {
        count++;

    }

    public void valueUnbound(HttpSessionBindingEvent arg0)
    {
        count--;

    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

}
//servlet
    public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException
    {
        String loginName = request.getParameter("loginName");
        HttpSession session = request.getSession();
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