IP 주소를 체크하는 정규 표현식.

문자열이 IP(0.0.0.0 ~ 255.255.255.255) 범위 안에 있는지 확인하기 위한 정규 표현식..

String ip1 = "127.0.0.1";
String ip2 = "255.255.255.255";
String ip3 = "255.255.255.256";

String ipRegex = "(\\d{1,2}|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d{1,2}|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d{1,2}|1\\d\\d|2[0-4]\\d|25[0-5])\\.(\\d{1,2}|1\\d\\d|2[0-4]\\d|25[0-5])";


System.out.println(ip1.matches(ipRegex));
System.out.println(ip2.matches(ipRegex));
System.out.println(ip3.matches(ipRegex));