如何在java中验证LEI校验和？

import java.util.regex.Pattern;

public class LEIValidator {
    public static boolean validateLEI(String lei) {
        // Check length
        if (lei.length() != 20) {
            return false;
        }

        // Check format
        String leiPattern = "[A-Za-z0-9]{4}[A-Za-z0-9]{12}";
        if (!Pattern.matches(leiPattern, lei)) {
            return false;
        }

        // Check checksum
        String digits = lei.substring(0, 18);
        int sum = 0;
        for (int i = 0; i < digits.length(); i++) {
            int digit = Character.getNumericValue(digits.charAt(i));
            sum = (sum * 10 + digit) % 97;
        }
        int checksum = (98 - sum) % 97;
        int expectedChecksum = Integer.parseInt(lei.substring(18));
        return checksum == expectedChecksum;
    }

    public static void main(String[] args) {
        String lei = "12345678901234567890";
        boolean isValid = validateLEI(lei);
        System.out.println("LEI is valid: " + isValid);
    }
}