java 简单实现ip地址与十进制的转换

可以使用 `InetAddress` 类来实现 IP 地址与十进制的转换。

将 IP 地址转为十进制：

import java.net.InetAddress;
import java.net.UnknownHostException;

public class IpToDecimal {
    public static void main(String[] args) {
        try {
            InetAddress address = InetAddress.getByName("192.168.0.1");
            byte[] bytes = address.getAddress();
            int result = 0;
            for (byte b : bytes) {
                result = result << 8 | (b & 0xFF);
            }
            System.out.println(result);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

将十进制转为 IP 地址：

import java.net.InetAddress;
import java.net.UnknownHostException;

public class DecimalToIp {
    public static void main(String[] args) {
        int decimal = 3232235521;
        byte[] bytes = new byte[]{
                (byte) ((decimal >> 24) & 0xFF),
                (byte) ((decimal >> 16) & 0xFF),
                (byte) ((decimal >> 8) & 0xFF),
                (byte) (decimal & 0xFF)
        };
        try {
            InetAddress address = InetAddress.getByAddress(bytes);
            System.out.println(address.getHostAddress());
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}