public class KeywordTimer implements ServletContextListener{

    private Logger log = Logger.getLogger(KeywordTimer.class);

    private Timer timer;

    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        timer.cancel();
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        timer =new Timer(true);
        timer.schedule(new TimerTask() {

            @Override
            public void run() {

                Dao dao = Mvcs.getIoc().get(Dao.class, "dao");
                System.out.println(dao == null);

            }
        },10*1000,1*15*1000);//3分钟
    }
}