IP地址/子网掩码解析类(仅支持C类IP)

public class IPSubnetUtil {
	public static final String IPADDRESS_REGEX = "(((2[0-4]\\d)|(25[0-5]))|(1\\d{2})|([1-9]\\d)|(\\d))[.](((2[0-4]\\d)|(25[0-5]))|(1\\d{2})|([1-9]\\d)|(\\d))[.](((2[0-4]\\d)|(25[0-5]))|(1\\d{2})|([1-9]\\d)|(\\d))[.](((2[0-4]\\d)|(25[0-5]))|(1\\d{2})|([1-9]\\d)|(\\d))";
    public static final String SUBNET_MASK_REGEX1 = "[/](255)[.](255)[.](255)[.]((0)|(128)|(192)|(224)|(240)|(248)|(252)|(254)|(255))";
    public static final String SUBNET_MASK_REGEX2 = "[/]((2[4-9])|(3[0-2]))";
    
    private static boolean inclusiveHostCount = false;

    /**
     * 避免被实例化
     */
    private IPSubnetUtil() {
    }
    
    /**
     * 通过IP/子网掩码得到IP地址列表, 仅支持C类IP(如 10.19.245.64/26 或 10.19.245.64/255.255.255.192)
     */

    public static List getWhiteIPBySubnetMask(String whiteIP) {
        List addressesList = new ArrayList();
        if (whiteIP.matches(IPADDRESS_REGEX + SUBNET_MASK_REGEX1)
                || whiteIP.matches(IPADDRESS_REGEX + SUBNET_MASK_REGEX2)) {
            String[] parts = whiteIP.split("/");
            long address = convertString2Ipaddr(parts[0]);
            long netmask = convertString2Mask(parts[1]);
            long network = getNetwork(address, netmask);
            long brodcast = getBrodcast(network, netmask);
            setIsInclusiveHostCount(parts[1]);
            for (long add = getLow(address, netmask, network); add <= getHigh(address, network, netmask, brodcast); ++add) {
                addressesList.add(format(toArray(add)));
            }
            return addressesList;
        } else {
            return addressesList;
        }
    }

    public static boolean validateIPFormat(String ip) {
        return ip.matches(IPADDRESS_REGEX) ? true : false;
    }

    /**
     * 得到第一个可用地址
     */
    private static long getLow(long address, long netmask, long network) {
        return (isInclusiveHostCount() ? getNetwork(address, netmask) : getBrodcast(network, netmask)
                - getNetwork(address, netmask) > 1 ? getNetwork(address, netmask) + 1 : 0);
    }

    /**
     * 得到网络地址
     */
    private static long getNetwork(long address, long netmask) {
        return (address & netmask);
    }

    /**
     * 得到最后一个可用地址
     */
    private static long getHigh(long address, long network, long netmask, long brodcast) {
        return (isInclusiveHostCount() ? getBrodcast(network, netmask) : getBrodcast(network, netmask)
                - getNetwork(address, netmask) > 1 ? getBrodcast(network, netmask) - 1 : 0);
    }

    /**
     * 得到广播地址
     */
    private static long getBrodcast(long network, long netmask) {
        return (network | ~(netmask)) & 0xffffffffl;
    }

    private static boolean isInclusiveHostCount() {
        return inclusiveHostCount;
    }

    /**
     * 若所给IP段有网络地址和广播地址, 则返回true
     */
    private static void setIsInclusiveHostCount(String netmask) {
    	inclusiveHostCount = netmask.equals("32") || netmask.equals("31") || netmask.equals("255.255.255.255")
                || netmask.equals("255.255.255.254") ? true : false;
    }

    /**
     * 将int数组转换为IP地址
     */
    private static String format(int[] octets) {
        StringBuilder str = new StringBuilder();
        for (int i = 0; i < octets.length; ++i) {
            str.append(octets[i]);
            if (i != octets.length - 1) {
                str.append(".");
            }
        }
        return str.toString();
    }

    /**
     * 将ip地址转换为int数组
     */
    private static int[] toArray(long val) {
        int ret[] = new int[4];
        for (int j = 3; j >= 0; --j) {
            ret[j] |= ((val >>> 8 * (3 - j)) & (0xff));
        }
        return ret;
    }

    /**
     * 得到子网掩码
     */
    private static long convertString2Mask(String mask) {
        return (mask.contains(".") ? convertString2Ipaddr(mask) : convertNum2Mask(mask));
    }

    /**
     * 将数字转换为子网掩码
     */
    private static long convertNum2Mask(String mask) {
        return (0xffffffffl << (32 - Integer.parseInt(mask))) & 0xffffffffl;
    }

    /**
     * IP地址转为整数型
     */
    private static long convertString2Ipaddr(String ip) {
        long ipv4 = 0x00;
        String[] ipArr = ip.split("\\.");
        for (int i = 0; i < ipArr.length; i++) {
            long seg = Long.parseLong(ipArr[i]);
            ipv4 = (ipv4 << 8) | seg;
        }
        return ipv4;
    }
}

参考了commons-net-3.1-bin.jar中的SubnetUtil.java类写成

返回的IP用List保存

未加入去重功能

请大家指教~