Credit Card Mod10 校验
/**
* Check whether a credit card number is valid or not according to the Luhn algorithm (MOD10).<br/>
* <br/>
* (Getting from http://en.wikipedia.org/wiki/Luhn_algorithm)<br/>
* 1. Counting from the check digit, which is the rightmost, and moving left, double the value of every second digit.<br/>
* 2. Sum the digits of the products together with the undoubled digits from the original number.<br/>
* 3. If the total ends in 0 (put another way, if the total modulo 10 is equal to 0), then the number
* is valid according to the Luhn formula; else it is not valid.<br/>
* <br/>
* As an illustration, if the account number is 49927398716, it will be validated as follows:<br/>
* i. Double every second digit, from the rightmost:<br/>
* (1×2) = 2, (8×2) = 16, (3×2) = 6, (2×2) = 4, (9×2) = 18<br/>
* ii. Sum all the individual digits (digits in parentheses are the products from Step 1):<br/>
* 6 + (2) + 7 + (1+6) + 9 + (6) + 7 + (4) + 9 + (1+8) + 4 = 70<br/>
* iii. Take the sum modulo 10: 70 mod 10 = 0; the account number is valid.<br/>
*
* @param num
* @return boolean true-valid; false-invalid
*/
public static boolean isValidCC(String num) {
// //Check digits
// if(!num.matches("^\\d{13,19}$"))
// return false;
//Check mod10
final int[][] sumTable = {{0,1,2,3,4,5,6,7,8,9},{0,2,4,6,8,1,3,5,7,9}};
int sum = 0, flip = 0;
for (int i = num.length() - 1; i >= 0; i--, flip++){
int n = num.charAt(i) - '0';
if (n < 0 || n > 9)
return false;
sum += sumTable[flip & 0x1][n];
}
return (sum == 0) ? false : (sum % 10 == 0);
}
/**
* Check whether a credit card number is valid or not according to the Luhn algorithm (MOD10).<br/>
* Used switch to double specified value.<br/>
*
* @param number
* @return
*/
public static boolean isValidCC1(String number) {
int sum = 0;
int mul = 1;
for (int i = number.length() - 1; i >= 0; i--) {
int n = number.charAt(i) - '0';
if (n < 0 || n > 9)
return false;
n *= (mul == 1) ? mul++ : mul--;
sum += (n>9 ? n-9 : n);
}
return (sum == 0) ? false : (sum % 10 == 0);
}
/**
* Check whether a credit card number is valid or not according to the Luhn algorithm (MOD10).<br/>
* Used position to double specified value.<br/>
*
* @param number
* @return
*/
public static boolean isValidCC2(String number) {
int sum = 0;
for (int i = number.length() - 1; i >= 0; i--) {
int n = number.charAt(i) - '0';
if (n < 0 || n > 9)
return false;
if ((number.length()-i)%2 == 0)
n *= 2;
sum += (n>9 ? n-9 : n);
}
return (sum == 0) ? false : (sum % 10 == 0);
}
/**
* Check whether a credit card number is valid or not according to the Luhn algorithm (MOD10).<br/>
* Used AND and XOR to double specified value.<br/>
* @param number
* @return
*/
public static boolean isValidCC3(String number) {
int digits = number.length();
int oddOrEven = digits & 1;
long sum = 0;
for (int i = 0; i < digits; i++) {
int n = number.charAt(i) - '0';
if (n < 0 || n > 9)
return false;
if (((i & 1) ^ oddOrEven) == 0)
n *= 2;
sum += (n>9 ? n-9 : n);
}
return (sum == 0) ? false : (sum % 10 == 0);
}
/**
* Check whether a credit card number is valid or not according to the Luhn algorithm (MOD10).<br/>
* Used a variable as switch to double specified value.
* @param number
* @return
*/
private static boolean isValidCC4(String number) {
int sum = 0;
boolean alternate = false;
for (int i = number.length() - 1; i >= 0; i--) {
int n = Integer.parseInt(number.substring(i, i + 1)); //May throw out a runtime exception
if (n < 0 || n > 9)
return false;
if (alternate)
n *= 2;
sum += (n>9 ? n%10 + 1 : n);
alternate = !alternate;
}
return (sum == 0) ? false : (sum % 10 == 0);
}
信用卡前缀及校验规则
| CARD TYPE | Prefix | Length | Check digit algorithm |
| MASTERCARD | 51-55 | 16 | mod 10 |
| VISA | 4 | 13, 16 | mod 10 |
| AMEX | 34 37 |
15 | mod 10 |
| Diners Club/ Carte Blanche |
300-305 36 38 |
14 | mod 10 |
| Discover | 6011 | 16 | mod 10 |
| enRoute | 2014 2149 |
15 | any |
| JCB | 3 | 16 | mod 10 |
| JCB | 2131 1800 |
15 | mod 10 |