/**
     * 校验银行卡号方法
     * @param bankCard
     * @return
     */
    public boolean checkBankCard(String bankCard) {
        if(bankCard.length() < 15 || bankCard.length() > 19) {
            return false;
        }
        char bit = getBankCardCheckCode(bankCard.substring(0, bankCard.length() - 1));
        if(bit == 'N'){
            return false;
        }
        return bankCard.charAt(bankCard.length() - 1) == bit;
    }


    /**
     * 从不含校验位的银行卡卡号采用 Luhm 校验算法获得校验位
     * @param nonCheckCodeBankCard
     * @return
     */
    public char getBankCardCheckCode(String nonCheckCodeBankCard){
        if(nonCheckCodeBankCard == null || nonCheckCodeBankCard.trim().length() == 0
                || !nonCheckCodeBankCard.matches("\\d+")) {
            //如果传的不是数据返回N
            return 'N';
        }
        char[] chs = nonCheckCodeBankCard.trim().toCharArray();
        int luhmSum = 0;
        for(int i = chs.length - 1, j = 0; i >= 0; i--, j++) {
            int k = chs[i] - '0';
            if(j % 2 == 0) {
                k *= 2;
                k = k / 10 + k % 10;
            }
            luhmSum += k;
        }
        return (luhmSum % 10 == 0) ? '0' : (char)((10 - luhmSum % 10) + '0');
    }