code: public static String getMacAddress(InetAddress inetAddress, String separator) {
  		if (null == inetAddress) {
  			return null;
  		}
  
  		byte[] mac;
  		try {
  			mac = NetworkInterface.getByInetAddress(inetAddress).getHardwareAddress();
  		} catch (SocketException e) {
  			throw new UtilException(e);
  		}
  		if (null != mac) {
  			final StringBuilder sb = new StringBuilder();
  			String s;
  			for (int i = 0; i < mac.length; i++) {
  				if (i != 0) {
  					sb.append(separator);
  				}
  				// 字节转换为整数
  				s = Integer.toHexString(mac[i] & 0xFF);
  				sb.append(s.length() == 1 ? 0 + s : s);
  			}
  			return sb.toString();
  		}
  		return null;
  	}
docs: 获得指定地址信息中的MAC地址
  
  @param inetAddress {@link InetAddress}
  @param separator 分隔符，推荐使用“-”或者“:”
  @return MAC地址，用-分隔