public static boolean isMaskValid(String mask) {
		return MaskBit.getMaskBit(mask) != null;
	}
@Test
	public void isMaskInvalidTest() {
		assertFalse(Ipv4Util.isMaskValid("255.255.0.255"), "掩码非法检验 - 255.255.0.255");
		assertFalse(Ipv4Util.isMaskValid(null), "掩码非法检验 - null值");
		assertFalse(Ipv4Util.isMaskValid(""), "掩码非法检验 - 空字符串");
		assertFalse(Ipv4Util.isMaskValid(" "), "掩码非法检验 - 空白字符串");
	}