利用Java语言编写不定长子网划分程序，输入需要划分的多个子网，并列出所有可用子网以及各子网IP范围

以下是一个简单的Java程序，可以实现不定长子网划分，并列出各子网IP范围：

import java.util.Scanner;

public class SubnetCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("请输入 IP 地址（例：192.168.0.1）：");
        String[] ipAddress = scanner.nextLine().split("\\.");

        int[] binaryIP = new int[32];
        for (int i = 0; i < 4; i++) {
            int octet = Integer.parseInt(ipAddress[i]);
            for (int j = 7; j >= 0; j--) {
                binaryIP[8 * i + 7 - j] = (octet >> j) & 1;
            }
        }

        System.out.print("请输入子网掩码（例：255.255.255.0）：");
        String[] subnetMask = scanner.nextLine().split("\\.");

        int[] binaryMask = new int[32];
        for (int i = 0; i < 4; i++) {
            int octet = Integer.parseInt(subnetMask[i]);
            for (int j = 7; j >= 0; j--) {
                binaryMask[8 * i + 7 - j] = (octet >> j) & 1;
            }
        }

        int subnetBits = 0;
        for (int i = 0; i < 32; i++) {
            if (binaryMask[i] == 1) {
                subnetBits++;
            } else {
                break;
            }
        }

        int numSubnets = (int) Math.pow(2, subnetBits);
        int numHosts = (int) Math.pow(2, 32 - subnetBits) - 2;

        System.out.println("可用子网数：" + numSubnets);
        System.out.println("每个子网可用主机数：" + numHosts);

        System.out.print("请输入需要划分的子网数：");
        int numDesiredSubnets = scanner.nextInt();

        int bitsToBorrow = (int) Math.ceil(Math.log(numDesiredSubnets) / Math.log(2));
        int newSubnetBits = subnetBits + bitsToBorrow;
        int newNumSubnets = (int) Math.pow(2, newSubnetBits);
        int newNumHosts = (int) Math.pow(2, 32 - newSubnetBits) - 2;

        System.out.println("需要借用 " + bitsToBorrow + " 位来划分 " + numDesiredSubnets + " 个子网");
        System.out.println("新子网掩码为：" + binaryMaskString(newSubnetBits));
        System.out.println("每个新子网可用主机数：" + newNumHosts);

        int[][] subnets = new int[numDesiredSubnets][32];
        int[][] ranges = new int[numDesiredSubnets][2];

        for (int i = 0; i < numDesiredSubnets; i++) {
            for (int j = 0; j < 32; j++) {
                if (j < subnetBits) {
                    subnets[i][j] = binaryIP[j];
                } else if (j < newSubnetBits) {
                    subnets[i][j] = 0;
                } else {
                    subnets[i][j] = (i >> (j - newSubnetBits)) & 1;
                }
            }
            ranges[i][0] = binaryIPToInt(subnets[i]);
            ranges[i][1] = ranges[i][0] + newNumHosts + 1;
        }

        System.out.println("子网\t起始地址\t结束地址");
        for (int i = 0; i < numDesiredSubnets; i++) {
            System.out.println((i + 1) + "\t" + intToIPAddress(ranges[i][0]) + "\t" + intToIPAddress(ranges[i][1] - 1));
        }
    }

    private static String binaryMaskString(int bits) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 32; i++) {
            if (i < bits) {
                sb.append("1");
            } else {
                sb.append("0");
            }
            if (i % 8 == 7) {
                sb.append(".");
            }
        }
        return sb.toString().substring(0, sb.length() - 1);
    }

    private static int binaryIPToInt(int[] binaryIP) {
        int num = 0;
        for (int i = 0; i < 32; i++) {
            num += binaryIP[i] * Math.pow(2, 31 - i);
        }
        return num;
    }

    private static String intToIPAddress(int num) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 4; i++) {
            sb.append(num / (int) Math.pow(256, 3 - i)).append(".");
            num %= (int) Math.pow(256, 3 - i);
        }
        return sb.toString().substring(0, sb.length() - 1);
    }
}

运行程序，按照提示输入 IP 地址和子网掩码，然后输入需要划分的子网数。程序会输出可用子网数、每个子网可用主机数、需要借用的位数、新子网掩码、每个新子网可用主机数以及各子网的起始地址和结束地址。