public static byte[] readBytes(InputStream in) throws IORuntimeException {
		return readBytes(in, true);
	}
@Test
	public void readBytesWithLengthTest() {
		// 读取固定长度
		final int limit = RandomUtil.randomInt(22807);
		final byte[] bytes = IoUtil.readBytes(ResourceUtil.getStream("hutool.jpg"), limit);
		assertEquals(limit, bytes.length);
	}