public static boolean safeSleep(Number millis) {
		if (millis == null) {
			return true;
		}

		return safeSleep(millis.longValue());
	}
@Test
	public void safeSleepTest() {
		final long sleepMillis = RandomUtil.randomLong(1, 1000);
		// 随机sleep时长，确保sleep时间足够
		final long l = System.currentTimeMillis();
		ThreadUtil.safeSleep(sleepMillis);
		assertTrue(System.currentTimeMillis() - l >= sleepMillis);
	}