Tomcat session数量能统计吗？该如何处理_J2EE

Tomcat session数量能统计吗？
如题

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个人认为可以：在application中定义一个数量，利用HttpSessionListener在session创建时＋1，session销毁时-1.
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Java code

package web;import javax.servlet.ServletContext;import javax.servlet.http.HttpSession;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;public class CountListener implements HttpSessionListener { private int count=0;    public void sessionCreated(HttpSessionEvent arg0) {        System.out.println("sessionCreated");        count++;        HttpSession session=arg0.getSession();        ServletContext sctx=session.getServletContext();        sctx.setAttribute("count", count);                    }    public void sessionDestroyed(HttpSessionEvent arg0) {        System.out.println("sessionDestroyed");        count--;        HttpSession session=arg0.getSession();        ServletContext sctx=session.getServletContext();        sctx.setAttribute("count", count);            }}
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Java codepackage com.test;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;class SessionCountListener implements HttpSessionListener{ public static long sessionCount=0;  @Override  public void sessionCreated(HttpSessionEvent arg0) {    sessionCount++;   }  @Override  public void sessionDestroyed(HttpSessionEvent arg0) {    // TODO Auto-generated method stub      }  }