在线用户数的统计

1.创建基础类

public class OnlineCounter {
    static Double onlinemenberLong = 0d;

    public static Double getOnlinemenberLong() {
        return onlinemenberLong;
    }

    public static void setOnlinemenberLong(Double onlinemenberLong) {
        OnlineCounter.onlinemenberLong = onlinemenberLong;
    }

    public static void raise() {
        onlinemenberLong++;
    }

    public static void reduce() {
        onlinemenberLong--;
    }
}

2.创建监听类:

public class OnlineCounterListener implements HttpSessionListener {

    public OnlineCounterListener() {
    }

    public void sessionCreated(HttpSessionEvent arg0) {
        OnlineCounter.raise();
    }

    public void sessionDestroyed(HttpSessionEvent arg0) {
        OnlineCounter.reduce();
    }
}

3.配置WEB.XML文件

        com.tw.util.OnlineCounterListener

4.输出在线用户

OnlineCounter.getOnlinemenberLong()