/** * Created by Administrator on 2016/9/18. * 验证银行卡格式是否正确 */public class CheckIdCard {    /**     * 校验银行卡卡号     *     * @param cardId     * @return     */    public static boolean checkBankCard(String cardId) {        char bit = getBankCardCheckCode(cardId                .substring(0, cardId.length() - 1));        if (bit == ‘N‘) {            return false;        }        return cardId.charAt(cardId.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 nonCheckCodeCardId     * @return     */    public static char getBankCardCheckCode(String nonCheckCodeCardId) {        if (nonCheckCodeCardId == null                || nonCheckCodeCardId.trim().length() == 0                || !nonCheckCodeCardId.matches("\\d+")) {            // 如果传的不是数据返回N            return ‘N‘;        }        char[] chs = nonCheckCodeCardId.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‘);    }}