在java中生成两个IP地址之间的所有IP地址

Question

I am trying to get all the IP addresses between the two addresses("168.200.197.3" and "238.199.200.78"). I splited the string to integer first. Then i tried to printout all addresses between these two. But the output only shows that each part of the address is being incremented, like 168 169 170...... I want the whole address to be increased(168.200.197.3, 168.200.197.4,168.200.197.5....etc). Please help !!!!!!!

public class IpAddress {


 public static void main(String[] args) {
    int [] ip1 = new int[4];
    int [] ip2 = new int[4];

    String [] parts1 = "168.200.197.3".split("\\.");
    String [] parts2 = "238.199.200.78".split("\\.");

    for (int i = 0; i <4; i++){
        ip1[i] = Integer.parseInt(parts1[i]);   
              for (int j = 0; j<4; j ++){
                    ip2[j] = Integer.parseInt(parts2[j]);
                           for (int k = ip1[i]; k<ip2[j]; k++){
                                  System.out.println(k);
                                        }
                                 }  
                        }
      }
}

Answer 1

An IPv4 address like abcd can be represented by an unsigned integer a*256^3+b*256^2+c*256+d . Now you can turn the two IP addresses into unsigned integers then you get an integer range, iterate the range and convert each unsigned integer back to IPv4 literal.

Answer 2

If it was me I would do this using an int value to represent the IP address and write a function that converts the int to a String representation of the IP:

private static final String getIPFromInt(final long ipaslong) {
    return String.format("%d.%d.%d.%d",
                (ipaslong >>> 24) & 0xff,
                (ipaslong >>> 16) & 0xff,
                (ipaslong >>>  8) & 0xff,
                (ipaslong       ) & 0xff);
}

Then I would calculate the start and end points by converting them to int representations (the opposite problem as the getIPFromLong(...) method, which I will leave as an exercise for you) and finally I would write a simple loop:

final long from = getLongFromIP(ip1);
final long to = getLongFromIP(ip2);

for (long i = from; i <= to, i++) {
    System.out.println(getIPFromLong(i);
}

EDIT: Changed loop argument i to be a long, and the other methods to accept long instead of int to avoid issues with integer sign bits.