JAVA类 | #识别有效的IP地址和掩码并进行分类统计#

import java.util.Arrays;
import java.util.Scanner;

class IP{
    int[] ip_array = new int[4];
    int[] mask_array = new int[4];

    public String ip_class;
    public boolean is_private;
    String mask2bi(int mask){
        StringBuffer sb = new StringBuffer(Integer.toBinaryString(mask));
        while(sb.length()!=8){
            sb.insert(0,'0');
        }
        return sb.toString();
    }
    IP(String ip, String mask){
        String[] ip_string_array = ip.split("\\.");
        String[] masks_string_array = mask.split("\\.");

        boolean mask_0 = false;

        if(ip_string_array.length!=4 || masks_string_array.length!=4) {
            ip_class = "invalid";
        }else{
            for(int i=0;i<4;i++){
                try{
                    int ip_parse = Integer.valueOf(ip_string_array[i]);
                    int mask_parse = Integer.valueOf(masks_string_array[i]);

                    ip_array[i] = ip_parse;
                    mask_array[i] = mask_parse;
                    if (ip_array[0]==0 || ip_array[0]==127) throw new Exception("non-count");
                    if(ip_parse<0 || ip_parse>255 || mask_parse<0 || mask_parse>255) throw new Exception("");

                    for(char c : mask2bi(mask_parse).toCharArray()){
                        if(c=='0') {
                            mask_0=true;
                        }else if(mask_0==true)
                            throw new Exception("");
                    }

                }catch (Exception e){
                    if(e.getMessage() == "non-count") ip_class = "non-count";
                    else ip_class = "invalid";
                    return;
                }


            }
            int mask_sum = Arrays.stream(mask_array).sum();

            if(mask_sum==0 || mask_sum==255*4) {
                ip_class = "invalid";

            }else{
                if (ip_array[0]<=126) {
                    ip_class = "A";
                }else if (ip_array[0]>=128 && ip_array[0]<=191) {
                    ip_class = "B";
                }else if (ip_array[0]>=192 && ip_array[0]<=223) {
                    ip_class = "C";
                }else if (ip_array[0]>=224 && ip_array[0]<=239) {
                    ip_class = "D";
                }else if (ip_array[0]>=240) {
                    ip_class = "E";
                }

                if(ip_array[0]==10 || (ip_array[0]==172 && ip_array[1]>=16 && ip_array[1]<=31) || (ip_array[0]==192 &&ip_array[1]==168)){
                    is_private = true;
                }else{
                    is_private = false;
                }
            }


        }

    }



}
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int A=0,B=0,C=0,D=0,E=0,Invalid=0,Private=0;
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String line = in.nextLine();
            if(line.equals(""))break;
            String[] line_split = line.split("~");

            IP ip = new IP(line_split[0],line_split[1]);
            switch (ip.ip_class){
                case "A":
                    A++;
                    break;
                case "B":
                    B++;
                    break;
                case "C":
                    C++;
                    break;
                case "D":
                    D++;
                    break;
                case "E":
                    E++;
                    break;
                case "invalid":
                    Invalid++;
                    break;

            }
            if(ip.is_private)Private++;

        }
        System.out.print(A);
        System.out.print(" ");
        System.out.print(B);
        System.out.print(" ");
        System.out.print(C);
        System.out.print(" ");
        System.out.print(D);
        System.out.print(" ");
        System.out.print(E);
        System.out.print(" ");
        System.out.print(Invalid);
        System.out.print(" ");
        System.out.print(Private);


    }
}

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