java 根据ipv6/掩码，获取所有ipv6

可以使用 `java.net.InetAddress` 类来实现根据 IPv6 和掩码获取所有 IPv6 的功能。具体的实现过程如下所示：

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

public class IPv6Utils {

    public static List<String> getAllIPv6(String ipv6, int mask) {
        List<String> allIPv6 = new ArrayList<>();
        try {
            InetAddress inetAddress = InetAddress.getByName(ipv6);
            byte[] addressBytes = inetAddress.getAddress();
            ByteBuffer buffer = ByteBuffer.wrap(addressBytes);

            int[] ipv6Bytes = new int[8];
            for (int i = 0; i < 8; i++) {
                ipv6Bytes[i] = buffer.getShort() & 0xffff;
            }

            int[] maskBytes = new int[8];
            for (int i = 0; i < 8; i++) {
                if (mask >= 16) {
                    maskBytes[i] = 0xffff;
                    mask -= 16;
                } else if (mask > 0) {
                    maskBytes[i] = (1 << mask) - 1;
                    mask = 0;
                }
            }

            int[] networkBytes = new int[8];
            for (int i = 0; i < 8; i++) {
                networkBytes[i] = ipv6Bytes[i] & maskBytes[i];
            }

            for (int i = networkBytes[0]; i <= (ipv6Bytes[0] | ~maskBytes[0]) & 0xffff; i++) {
                for (int j = networkBytes[1]; j <= (ipv6Bytes[1] | ~maskBytes[1]) & 0xffff; j++) {
                    for (int k = networkBytes[2]; k <= (ipv6Bytes[2] | ~maskBytes[2]) & 0xffff; k++) {
                        for (int l = networkBytes[3]; l <= (ipv6Bytes[3] | ~maskBytes[3]) & 0xffff; l++) {
                            for (int m = networkBytes[4]; m <= (ipv6Bytes[4] | ~maskBytes[4]) & 0xffff; m++) {
                                for (int n = networkBytes[5]; n <= (ipv6Bytes[5] | ~maskBytes[5]) & 0xffff; n++) {
                                    for (int o = networkBytes[6]; o <= (ipv6Bytes[6] | ~maskBytes[6]) & 0xffff; o++) {
                                        for (int p = networkBytes[7]; p <= (ipv6Bytes[7] | ~maskBytes[7]) & 0xffff; p++) {
                                            StringBuilder sb = new StringBuilder();
                                            sb.append(String.format("%x", i)).append(":")
                                                    .append(String.format("%x", j)).append(":")
                                                    .append(String.format("%x", k)).append(":")
                                                    .append(String.format("%x", l)).append(":")
                                                    .append(String.format("%x", m)).append(":")
                                                    .append(String.format("%x", n)).append(":")
                                                    .append(String.format("%x", o)).append(":")
                                                    .append(String.format("%x", p));
                                            allIPv6.add(sb.toString());
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

        return allIPv6;
    }
}

其中，输入参数为 IPv6 地址和掩码长度，返回结果为符合该掩码的所有 IPv6 地址的列表。