不要试图检测信用卡类型作为处理支付的一部分。您正在冒着拒绝有效事务的风险。

如果您需要向您的支付处理器提供信息(例如，PayPal信用卡对象需要命名卡类型)，那么从可用的最少信息中猜测它，例如。

$credit_card['pan'] = preg_replace('/[^0-9]/', '', $credit_card['pan']);
$inn = (int) mb_substr($credit_card['pan'], 0, 2);

// @see http://en.wikipedia.org/wiki/List_of_Bank_Identification_Numbers#Overview
if ($inn >= 40 && $inn <= 49) {
    $type = 'visa';
} else if ($inn >= 51 && $inn <= 55) {
    $type = 'mastercard';
} else if ($inn >= 60 && $inn <= 65) {
    $type = 'discover';
} else if ($inn >= 34 && $inn <= 37) {
    $type = 'amex';
} else {
    throw new \UnexpectedValueException('Unsupported card type.');
}

这个实现(只使用前两位数字)足以识别所有主要的(在PayPal的情况下是所有受支持的)卡片方案。实际上，您可能希望完全跳过异常，并默认使用最流行的卡片类型。让支付网关/处理器告诉您在响应您的请求时是否存在验证错误。

现实情况是，你的支付网关并不关心你提供的价值。

我用jQuery的解决方案:

function detectCreditCardType() {
    var type = new Array;
    type[1] = '^4[0-9]{12}(?:[0-9]{3})?$';      // visa
    type[2] = '^5[1-5][0-9]{14}$';              // mastercard
    type[3] = '^6(?:011|5[0-9]{2})[0-9]{12}$';  // discover
    type[4] = '^3[47][0-9]{13}$';               // amex

    var ccnum = $('.creditcard').val().replace(/[^\d.]/g, '');
    var returntype = 0;

    $.each(type, function(idx, re) {
        var regex = new RegExp(re);
        if(regex.test(ccnum) && idx>0) {
            returntype = idx;
        }
    });

    return returntype;
}

如果返回0，则未检测到信用卡类型。

“creditcard”类应该添加到creditcard输入字段中。

follow Luhn’s algorithm

 private  boolean validateCreditCardNumber(String str) {

        int[] ints = new int[str.length()];
        for (int i = 0; i < str.length(); i++) {
            ints[i] = Integer.parseInt(str.substring(i, i + 1));
        }
        for (int i = ints.length - 2; i >= 0; i = i - 2) {
            int j = ints[i];
            j = j * 2;
            if (j > 9) {
                j = j % 10 + 1;
            }
            ints[i] = j;
        }
        int sum = 0;
        for (int i = 0; i < ints.length; i++) {
            sum += ints[i];
        }
        if (sum % 10 == 0) {
           return true;
        } else {
            return false;
        }


    }

then call this method

Edittext mCreditCardNumberEt;

 mCreditCardNumberEt.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

             int cardcount=   s.toString().length();
                 if(cardcount>=16) {
                    boolean cardnumbervalid=   validateCreditCardNumber(s.toString());
                    if(cardnumbervalid) {
                        cardvalidtesting.setText("Valid Card");
                        cardvalidtesting.setTextColor(ContextCompat.getColor(context,R.color.green));
                    }
                    else {
                        cardvalidtesting.setText("Invalid Card");
                        cardvalidtesting.setTextColor(ContextCompat.getColor(context,R.color.red));
                    }
                }
               else if(cardcount>0 &&cardcount<16) {
                     cardvalidtesting.setText("Invalid Card");
                     cardvalidtesting.setTextColor(ContextCompat.getColor(context,R.color.red));
                }

                else {
                    cardvalidtesting.setText("");

                }


                }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

看看这个:

http://www.breakingpar.com/bkp/home.nsf/0/87256B280015193F87256CC70060A01B

function isValidCreditCard(type, ccnum) {
    /* Visa: length 16, prefix 4, dashes optional.
    Mastercard: length 16, prefix 51-55, dashes optional.
    Discover: length 16, prefix 6011, dashes optional.
    American Express: length 15, prefix 34 or 37.
    Diners: length 14, prefix 30, 36, or 38. */

    var re = new Regex({
        "visa": "/^4\d{3}-?\d{4}-?\d{4}-?\d",
        "mc": "/^5[1-5]\d{2}-?\d{4}-?\d{4}-?\d{4}$/",
        "disc": "/^6011-?\d{4}-?\d{4}-?\d{4}$/",
        "amex": "/^3[47]\d{13}$/",
        "diners": "/^3[068]\d{12}$/"
    }[type.toLowerCase()])

    if (!re.test(ccnum)) return false;
    // Remove all dashes for the checksum checks to eliminate negative numbers
    ccnum = ccnum.split("-").join("");
    // Checksum ("Mod 10")
    // Add even digits in even length strings or odd digits in odd length strings.
    var checksum = 0;
    for (var i = (2 - (ccnum.length % 2)); i <= ccnum.length; i += 2) {
        checksum += parseInt(ccnum.charAt(i - 1));
    }
    // Analyze odd digits in even length strings or even digits in odd length strings.
    for (var i = (ccnum.length % 2) + 1; i < ccnum.length; i += 2) {
        var digit = parseInt(ccnum.charAt(i - 1)) * 2;
        if (digit < 10) { checksum += digit; } else { checksum += (digit - 9); }
    }
    if ((checksum % 10) == 0) return true;
    else return false;
}

anatoly用PHP回答:

 public static function detectCardType($num)
 {
    $re = array(
        "visa"       => "/^4[0-9]{12}(?:[0-9]{3})?$/",
        "mastercard" => "/^5[1-5][0-9]{14}$/",
        "amex"       => "/^3[47][0-9]{13}$/",
        "discover"   => "/^6(?:011|5[0-9]{2})[0-9]{12}$/",
    );

    if (preg_match($re['visa'],$num))
    {
        return 'visa';
    }
    else if (preg_match($re['mastercard'],$num))
    {
        return 'mastercard';
    }
    else if (preg_match($re['amex'],$num))
    {
        return 'amex';
    }
    else if (preg_match($re['discover'],$num))
    {
        return 'discover';
    }
    else
    {
        return false;
    }
 }

Stripe提供了这个很棒的javascript库来检测卡片方案。让我添加一些代码片段，并向您展示如何使用它。

首先包括它到你的网页作为

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery.payment/1.2.3/jquery.payment.js " ></script>

其次，利用功能cardType来检测卡片方案。

$(document).ready(function() {              
            var type = $.payment.cardType("4242 4242 4242 4242"); //test card number
            console.log(type);                                   
}); 

这里有更多示例和演示的参考链接。

Stripe博客的jquery.payment.js Github库