银行卡号四分位处理

/**
* desc: 处理银行卡号格式
* @param bankCardNum
* @return {@link String}
*/
private String handleBankCardNum(String bankCardNum) {
String bankCardStr = "";
if (StringUtil.isNotBlank(bankCardNum)) {
bankCardStr = handleBankCard(bankCardNum);
}
return bankCardStr;
}

private String handleBankCard(String bankCardNum) {
String str = "";
if (StringUtil.isNotBlank(bankCardNum)) {
if (bankCardNum.length() >= 4) {
str = bankCardNum.substring(0, 4) + " ";
String substring = bankCardNum.substring(4);
str += handleBankCard(substring);
} else {
str += bankCardNum;
}
}
return str;
}