问如何计算web服务客户端空闲时间

EN

public class KPHearBeat {

    private static Timer timer;
    static{
        timer = new Timer();
    }

    public String callWebService(int input){

        timer.cancel();
        System.out.println("calling my webService");
        startTimer();
        System.out.println("Starting timer");
        return "Done";
    }

    private void startTimer() {
        timer.purge();
        timer = new Timer();
        timer.scheduleAtFixedRate(new TimerTask() {

            @Override
            public void run() {

                System.out.println("Calling Heart Beat service");

            }
        }, 10000, 10000);
    }

}

public class KPTestTimer {

    @Test
    public void testTimer(){

        KPHearBeat kp = new KPHearBeat();

        kp.callWebService(1);
        try {
            Thread.currentThread().sleep(15000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        kp.callWebService(2);
        try {
            Thread.currentThread().sleep(8000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        kp.callWebService(3);
        try {
            Thread.currentThread().sleep(25000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}