Java隨機產生信用卡卡號的代碼__Java

import java.util.List;import java.util.Stack;import java.util.Vector;/** * See the license below. Obviously, this is not a Javascript credit card number * generator. However, The following class is a port of a Javascript credit card * number generator. * * @author robweber * */public class RandomCreditCardNumberGenerator {    /*     * Javascript credit card number generator Copyright (C) 2006-2012 Graham King     *     * This program is free software; you can redistribute it and/or modify it     * under the terms of the GNU General Public License as published by the     * Free Software Foundation; either version 2 of the License, or (at your     * option) any later version.     *     * This program is distributed in the hope that it will be useful, but     * WITHOUT ANY WARRANTY; without even the implied warranty of     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General     * Public License for more details.     *     * You should have received a copy of the GNU General Public License along     * with this program; if not, write to the Free Software Foundation, Inc.,     * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.     *     * www.darkcoding.net     */    public static final String[] VISA_PREFIX_LIST = new String[] { "4539",            "4556", "4916", "4532", "4929", "40240071", "4485", "4716", "4" };    public static final String[] MASTERCARD_PREFIX_LIST = new String[] { "51",            "52", "53", "54", "55" };    public static final String[] AMEX_PREFIX_LIST = new String[] { "34", "37" };    public static final String[] DISCOVER_PREFIX_LIST = new String[] { "6011" };    public static final String[] DINERS_PREFIX_LIST = new String[] { "300",            "301", "302", "303", "36", "38" };    public static final String[] ENROUTE_PREFIX_LIST = new String[] { "2014",            "2149" };    public static final String[] JCB_PREFIX_LIST = new String[] { "35" };    public static final String[] VOYAGER_PREFIX_LIST = new String[] { "8699" };    static String strrev(String str) {        if (str == null)            return "";        String revstr = "";        for (int i = str.length() - 1; i >= 0; i--) {            revstr += str.charAt(i);        }        return revstr;    }    /*     * 'prefix' is the start of the CC number as a string, any number of digits.     * 'length' is the length of the CC number to generate. Typically 13 or 16     */    static String completed_number(String prefix, int length) {        String ccnumber = prefix;        // generate digits        while (ccnumber.length() < (length - 1)) {            ccnumber += new Double(Math.floor(Math.random() * 10)).intValue();        }        // reverse number and convert to int        String reversedCCnumberString = strrev(ccnumber);        List<Integer> reversedCCnumberList = new Vector<Integer>();        for (int i = 0; i < reversedCCnumberString.length(); i++) {            reversedCCnumberList.add(new Integer(String                    .valueOf(reversedCCnumberString.charAt(i))));        }        // calculate sum        int sum = 0;        int pos = 0;        Integer[] reversedCCnumber = reversedCCnumberList                .toArray(new Integer[reversedCCnumberList.size()]);        while (pos < length - 1) {            int odd = reversedCCnumber[pos] * 2;            if (odd > 9) {                odd -= 9;            }            sum += odd;            if (pos != (length - 2)) {                sum += reversedCCnumber[pos + 1];            }            pos += 2;        }        // calculate check digit        int checkdigit = new Double(                ((Math.floor(sum / 10) + 1) * 10 - sum) % 10).intValue();        ccnumber += checkdigit;        return ccnumber;    }    public static String[] credit_card_number(String[] prefixList, int length,            int howMany) {        Stack<String> result = new Stack<String>();        for (int i = 0; i < howMany; i++) {            int randomArrayIndex = (int) Math.floor(Math.random()                    * prefixList.length);            String ccnumber = prefixList[randomArrayIndex];            result.push(completed_number(ccnumber, length));        }        return result.toArray(new String[result.size()]);    }    public static String[] generateMasterCardNumbers(int howMany) {        return credit_card_number(MASTERCARD_PREFIX_LIST, 16, howMany);    }    public static String generateMasterCardNumber() {        return credit_card_number(MASTERCARD_PREFIX_LIST, 16, 1)[0];    }    public static boolean isValidCreditCardNumber(String creditCardNumber) {        boolean isValid = false;        try {            String reversedNumber = new StringBuffer(creditCardNumber)                    .reverse().toString();            int mod10Count = 0;            for (int i = 0; i < reversedNumber.length(); i++) {                int augend = Integer.parseInt(String.valueOf(reversedNumber                        .charAt(i)));                if (((i + 1) % 2) == 0) {                    String productString = String.valueOf(augend * 2);                    augend = 0;                    for (int j = 0; j < productString.length(); j++) {                        augend += Integer.parseInt(String.valueOf(productString                                .charAt(j)));                    }                }                mod10Count += augend;            }            if ((mod10Count % 10) == 0) {                isValid = true;            }        } catch (NumberFormatException e) {        }        return isValid;    }    public static void main(String[] args) {        int howMany = 0;        try {            howMany = Integer.parseInt(args[0]);        } catch (Exception e) {            System.err                    .println("Usage error. You need to supply a numeric argument (ex: 500000)");        }        String[] creditcardnumbers = generateMasterCardNumbers(howMany);        for (int i = 0; i < creditcardnumbers.length; i++) {            System.out.println(creditcardnumbers[i]                    + ":"                    + (isValidCreditCardNumber(creditcardnumbers[i]) ? "valid"                            : "invalid"));        }    }}//該程式碼片段來自於: http://www.sharejs.com/codes/java/7103