随笔分类(157)

可以采用cookies和sessionid的做法，这里是使用sessionid的做法。
使用HttpSessionListener来监听session的创建和销毁，集群内部的tomcat开启session复制。2个应用都试用HttpSessionListener来监听

web.xml：

  <listener>
  <listener-class>com.com.ActiveUserListener2</listener-class>
 </listener>

<distributable/>

ActiveUserListener2.java

package com.com;

import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class ActiveUserListener2 implements HttpSessionListener {
    private static int sessionCount2 = 0;
    private static Map sessionMaps2 = new HashMap(); //存放session的集合类

  public void sessionCreated(HttpSessionEvent arg0) {
        HttpSession session = arg0.getSession();
        String sessionId = session.getId();
        System.out.println("Create a session:" + sessionId);
        sessionMaps2.put(sessionId, session);
        sessionCount2++;
 }

  public void sessionDestroyed(HttpSessionEvent arg0) {
        sessionCount2--;
        String sessionId = arg0.getSession().getId();
        sessionMaps2.remove(sessionId);//利用会话ID标示特定会话
        System.out.println("Destroy a session:" + sessionId);
 }
 public static int getSessionCount() {
  return sessionCount2;
    }
    public static Map getSessionMaps() {
     return sessionMaps2;
    }
}

传递sessionid，?jsessionid=<%=session.getId()%>

测试效果：
<%
Map activeSessions = ActiveUserListener2.getSessionMaps();
             out.println(activeSessions.get("CB55ABC39DD5B917D65F456C28FC25E6.tomcat1"));
             out.println(activeSessions);
            }
      }
%>