modulo10.java

这是个国外JAVA爱好者写的条形码生成器

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package net.sourceforge.barbecue;

/**
 * Modulo 10 Check Sum class.
 *
 * @author <a href="mailto:[e-mail]">James Jenner</a>
 */
public class Modulo10 {
    
    /* no public access */
    private Modulo10() {
    }
    
    /**
     * Calculates a modulo 10 check digit based on the passed numeric data.
     * The calculated check sum is determined using the weighted values, if
     * there is a need for no weight to be applied against the odd and/or 
     * even characters then use the value 1.
     * If a non-numeric value is within the data then NumberFormatException 
     * will be thrown.
     * @param data The data to encode into a Modulo 10 check digit
     * @param weightEven Every even digit will be multiplied by this value
     * @param weightOdd Every odd digit will be multiplied by this value
     * @param beginsEven true if the first numeric data is to be treated as even,
     * false if the first digit is to be treated as odd
     * @return the numeric value of the check digit calculated
     * @see #getMod10CheckDigit(String, int, int)
     * @see #getMod10CheckDigit(String, int)
     */
    public static int getMod10CheckDigit(String data, int weightEven, int weightOdd, boolean beginsEven) 
      throws java.lang.NumberFormatException {
        int sum = 0;
        int len = data.length();
        int value;
        int compareValue = beginsEven ? 0 : 1;
        int result = 0;
        
        for(int i = 0; i < len; i++) {
            value = Integer.parseInt(String.valueOf(data.charAt(i)));
            sum += (i % 2) == compareValue ? weightEven * value : weightOdd * value;
        }

        result = 10 - (sum % 10);

        if(result == 10) {
            result = 0;
        }

        return result;
    }

    /**
     * Calculates a modulo 10 check digit based on the passed numeric data.
     * The calculated check sum is determined using the weighted values, if
     * there is a need for no weight to be applied against the odd and/or 
     * even characters then use the value 1.
     * If a non-numeric value is within the data then NumberFormatException 
     * will be thrown.
     * The first value of data is treated as even.
     * @param data The data to encode into a Modulo 10 check digit
     * @param weightEven Every even digit will be multiplied by this value
     * @param weightOdd Every odd digit will be multiplied by this value
     * false if the first digit is to be treated as odd
     * @return the numeric value of the check digit calculated
     * @see #getMod10CheckDigit(String, int)
     */
    public static int getMod10CheckDigit(String data, int weightEven, int weightOdd) 
      throws java.lang.NumberFormatException {
        return getMod10CheckDigit(data, weightEven, weightOdd, true);
    }
    
    /**
     * Calculates a modulo 10 check digit based on the passed numeric data.
     * The only weight available is odd, this is a common usage.
     * If a non-numeric value is within the data then NumberFormatException 
     * will be thrown.
     * The first value of data is treated as even.
     * @param data The data to encode into a Modulo 10 check digit
     * @param weightOdd Every odd digit will be multiplied by this value
     * @return the numeric value of the check digit calculated
     * @see #getMod10CheckDigit(String, int, int)
     */
    public static int getMod10CheckDigit(String data, int weightOdd) throws java.lang.NumberFormatException {
        return getMod10CheckDigit(data, 1, weightOdd, true);
    }
}