session通过监听器存入全局MAP存入

package com.hbsc.util;

import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
@WebListener
public class MySessionListener implements HttpSessionListener {

    @Override
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        MySessionContext.AddSession(httpSessionEvent.getSession());
    }

    @Override
    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {
        HttpSession session = httpSessionEvent.getSession();
        MySessionContext.DelSession(session);
    }
}

package com.hbsc.util;

import javax.servlet.http.HttpSession;
import java.util.HashMap;

public class MySessionContext {
    private static HashMap mymap = new HashMap();

    public static synchronized void AddSession(HttpSession session) {
        if (session != null) {
            mymap.put(session.getId(), session);
        }
    }

    public static synchronized void DelSession(HttpSession session) {
        if (session != null) {
            mymap.remove(session.getId());
        }
    }

    public static synchronized HttpSession getSession(String session_id) {
        if (session_id == null) {
            return null;
        }
        return (HttpSession) mymap.get(session_id);
    }
}