java - 如何检查 IBAN 验证？

Question

如何在 Java 中验证 IBAN（国际银行帐号）以在 Android 应用程序中使用？

国际银行帐号是一种国际公认的识别跨国银行账户的系统，以促进跨境交易的沟通和处理，同时降低转录错误的风险。

Answer 1

private boolean isIbanValid(String iban) {

    int IBAN_MIN_SIZE = 15;
    int IBAN_MAX_SIZE = 34;
    long IBAN_MAX = 999999999;
    long IBAN_MODULUS = 97;

    String trimmed = iban.trim();

    if (trimmed.length() < IBAN_MIN_SIZE || trimmed.length() > IBAN_MAX_SIZE) {
        return false;
    }

    String reformat = trimmed.substring(4) + trimmed.substring(0, 4);
    long total = 0;

    for (int i = 0; i < reformat.length(); i++) {

        int charValue = Character.getNumericValue(reformat.charAt(i));

        if (charValue < 0 || charValue > 35) {
            return false;
        }

        total = (charValue > 9 ? total * 100 : total * 10) + charValue;

        if (total > IBAN_MAX) {
            total = (total % IBAN_MODULUS);
        }
    }

    return (total % IBAN_MODULUS) == 1;
}

Answer 2

要实施这些步骤：https ://en.wikipedia.org/wiki/International_Bank_Account_Number#Validating_the_IBAN

此外，long 太小而无法容纳数字。你需要一个大整数。

private boolean isIbanValid(String iban) {
    // remove spaces
    iban = iban.replace("\\s", "");

    // make all uppercase
    iban = iban.toUpperCase();

    // check length - complicated, depends on country. Skipping for now.
    // https://en.wikipedia.org/wiki/International_Bank_Account_Number#Structure

    // move first four letters to the end
    iban = iban.substring(4) + iban.substring(0,4);

    // convert letters to digits
    String total = "";
    for (int i = 0; i < iban.length(); i++) {

        int charValue = Character.getNumericValue(iban.charAt(i));

        if (charValue < 0 || charValue > 35) {
            return false;
        }

        total += charValue;
    }

    // Make BigInteger and check if modulus 97 is 1 
    BigInteger totalInt = new BigInteger(total);
    return totalInt.mod(new BigInteger("97")).equals(BigInteger.ONE);
}