JAVA 定时器 ScheduledThreadPoolExecutor

...
		//定时器
		ScheduledThreadPoolExecutor monitorService = new ScheduledThreadPoolExecutor(10, new ThreadFactoryBuilder().setNameFormat("lifecycleSupervisor-" + Thread.currentThread().getId() + "-%d").build());
		//最大20个线程
		monitorService.setMaximumPoolSize(20);
		//空闲30秒就收回
		monitorService.setKeepAliveTime(30, TimeUnit.SECONDS);

		ScheduledFuture future = monitorService.scheduleWithFixedDelay(new Runnable() {
			@Override
			public void run() {
				System.out.println(new Date());
			}
		}, 0, 3, TimeUnit.SECONDS);
...