[Java] Base64 encode & decode & isBase64

public static String encodeBase64(String s) {
	return Base64.getEncoder().encodeToString(s.getBytes());
}

public static String decodeBase64(String s) {
	try {
		if (isBase64(s)) {
			return new String(Base64.getDecoder().decode(s));
		} else {
			return s;
		}
	} catch (Exception e) {
		return s;
	}
}

public static boolean isBase64(String s) {
	String pattern = "^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$";
	Pattern r = Pattern.compile(pattern);
	Matcher m = r.matcher(s);

	return m.find();
}

https://stackoverflow.com/questions/8571501/how-to-check-whether-a-string-is-base64-encoded-or-not/70254838#70254838

How to check whether a string is Base64 encoded or not

 

https://www.baeldung.com/java-base64-encode-and-decode

https://dev-syhy.tistory.com/15

[Java] base64 인코딩 디코딩 (encoding / decoding)

https://stackoverflow.com/questions/8571501/how-to-check-whether-a-string-is-base64-encoded-or-not

How to check whether a string is Base64 encoded or not