SystemClock.java 文件源码

private void scheduleClockUpdating() {
    ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor(new ThreadFactory() {
        @Override
        public Thread newThread(Runnable runnable) {
            Thread thread = new Thread(runnable, "System Clock");
            thread.setDaemon(true);
            return thread;
        }
    });
    scheduler.scheduleAtFixedRate(new Runnable() {
        @Override
        public void run() {
            now.set(System.currentTimeMillis());
        }
    }, precision, precision, TimeUnit.MILLISECONDS);
}