自定义session扫描器精确控制session销毁时间--学习笔记

package cn.xijie.listener;import java.util.ArrayList;import java.util.Collections;import java.util.Date;import java.util.List;import java.util.ListIterator;import java.util.Timer;import java.util.TimerTask;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.http.HttpSession;import javax.servlet.http.HttpSessionEvent;import javax.servlet.http.HttpSessionListener;//HttpSession扫描器public class SessionScanner implements ServletContextListener,HttpSessionListener{    private List<HttpSession> sessionList = new ArrayList<HttpSession>();    //线程安全    private Timer timer = new Timer();    public SessionScanner(){        //将线程不安全的List转换成线程安全的List        sessionList = Collections.synchronizedList(sessionList);    }    //ServletContext产生    public void contextInitialized(ServletContextEvent sce) {        timer.schedule(new SessionTask(this.sessionList),0,1*1000);    }    //HttpSession产生    public void sessionCreated(HttpSessionEvent se) {        //取得客户端产生的HttpSession        HttpSession session = se.getSession();        System.out.println("HttpSession产生" + session.hashCode() + new Date().toLocaleString());        synchronized (sessionList) {            //将HttpSession加入到容器中            this.sessionList.add(session);        }    }    //ServletContext销毁    public void contextDestroyed(ServletContextEvent sce) {        timer.cancel();    }    //HttpSession销毁    public void sessionDestroyed(HttpSessionEvent se) {        HttpSession session = se.getSession();        System.out.println("HttpSession销毁" + session.hashCode() + new Date().toLocaleString());    }}//任务类class SessionTask extends TimerTask{    private List<HttpSession> sessionList;    public SessionTask(List<HttpSession> sessionList) {        this.sessionList = sessionList;    }    public void run() {        System.out.println("run()");        //迭代集合        //Iterator<HttpSession> it = sessionList.iterator();        synchronized (sessionList) {            ListIterator<HttpSession> it = sessionList.listIterator();            while (it.hasNext()) {                HttpSession session = it.next();                //判段HttpSession是否1分钟未被使用                int middle = (int) ((System.currentTimeMillis() - session                        .getLastAccessedTime()) / 1000);                if (middle > 60) {                    //将该HttpSession销毁                    session.invalidate();                    //从集合中删除该HttpSession ....有可能出现并发问题                    //sessionList.remove(session);                    it.remove();                }            }        }    }}

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HttpSession产生6027721002018-4-20 14:47:32
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HttpSession销毁6027721002018-4-20 14:48:45
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