（使用newScheduledThreadPool來模擬心跳機制）

 1 public class HeartBeat {
 2     public static void main(String[] args) {
 3         ScheduledExecutorService executor = Executors.newScheduledThreadPool(5);
 4         Runnable task = new Runnable() {
 5             public void run() {
 6                 System.out.println("HeartBeat.........................");
 7             }
 8         };
 9         executor.scheduleAtFixedRate(task,5,3, TimeUnit.SECONDS);   //5秒後第一次執行，之後每隔3秒執行一次
10     }
11 }

HeartBeat....................... //5秒後第一次輸出
HeartBeat....................... //每隔3秒輸出一個