Ip总量计算工具

以你之姓@ 2023-02-11 07:16 78阅读 0赞

# Ip总量计算工具 #

/** * <功能简要> <br> * <ip段,ip总数计算工具> * * @Author heyanbo * @createTime 2020/5/6 23:15 * @since 1.0 */
    public class IPTotalUtil { 
    
        public static void main(String[] args) { 
            Integer ipTotal = getIpTotal("192.168.0.1/20");
            System.out.println(ipTotal);
        }
    
        /** * 获取ip段中的ip数量 * 例:192.168.0.1/16 * 计算公式： 2^(32-16) * @param cidr * @return */
        public static Integer getIpTotal(String cidr){ 
            String[] split = cidr.split("/");
            Integer num = Integer.valueOf(split[1]);
            return powerTwo(32 - num);
        }
    
        /** * 计算2的倍数 * @param N * @return */
        public static int powerTwo(int N) { 
            StringBuilder stringBuilder = new StringBuilder("");
            long num[] = new long[2];
            num[1] = 1;
            if (N > 62) { 
                num[0] = 1;
                num[0] = num[0] << (N - 62);
                num[1] = num[1] << 62;
                String s = String.valueOf(num[1]);
                int size = 30, i = 0, j = 0;
                long n[] = new long[size + 1];
                for (i = s.length() - 1; i >= 0; --i) { 
                    n[j++] = (long) (num[0] * (s.charAt(i) - '0'));
                }
                for (i = 0; i < size; ++i) { 
                    while (n[i] > 9) { 
                        n[i + 1] += n[i] / 10;
                        n[i] %= 10;
                    }
                }
                boolean bl = false;
                for (i = size; i >= 0; --i) { 
                    if (n[i] != 0 || bl) { 
                        stringBuilder.append(n[i]);
                        bl = true;
                    }
                }
            } else { 
                //左移运算符
                num[1] = num[1] << N;
                stringBuilder.append(String.valueOf(num[1]));
            }
            return Integer.valueOf(stringBuilder.toString());
        }
    }