ModulusTenCheckDigit.java
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* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
* limitations under the License.
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package org.apache.commons.validator.routines.checkdigit;
import java.util.Arrays;
import org.apache.commons.validator.GenericValidator;
import org.apache.commons.validator.routines.CodeValidator;
/**
* General Modulus 10 Check Digit calculation/validation.
*
* <h2>How it Works</h2>
* <p>
* This implementation calculates/validates the check digit in the following
* way:
* <ul>
* <li>Converting each character to an integer value using
* <code>Character.getNumericValue(char)</code> - negative integer values from
* that method are invalid.</li>
* <li>Calculating a <i>weighted value</i> by multiplying the character's
* integer value by a <i>weighting factor</i>. The <i>weighting factor</i> is
* selected from the configured <code>postitionWeight</code> array based on its
* position. The <code>postitionWeight</code> values are used either
* left-to-right (when <code>useRightPos=false</code>) or right-to-left (when
* <code>useRightPos=true</code>).</li>
* <li>If <code>sumWeightedDigits=true</code>, the <i>weighted value</i> is
* re-calculated by summing its digits.</li>
* <li>The <i>weighted values</i> of each character are totalled.</li>
* <li>The total modulo 10 will be zero for a code with a valid Check Digit.</li>
* </ul>
* <h2>Limitations</h2>
* <p>
* This implementation has the following limitations:
* <ul>
* <li>It assumes the last character in the code is the Check Digit and
* validates that it is a numeric character.</li>
* <li>The only limitation on valid characters are those that
* <code>Character.getNumericValue(char)</code> returns a positive value. If,
* for example, the code should only contain numbers, this implementation does
* not check that.</li>
* <li>There are no checks on code length.</li>
* </ul>
* <p>
* <b>Note:</b> This implementation can be combined with the
* {@link CodeValidator} in order to ensure the length and characters are valid.
*
* <h2>Example Usage</h2>
* <p>
* This implementation was added after a number of Modulus 10 routines and these
* are shown re-implemented using this routine below:
*
* <p>
* <b>ABA Number</b> Check Digit Routine (equivalent of
* {@link ABANumberCheckDigit}). Weighting factors are <code>[1, 7, 3]</code>
* applied from right to left.
*
* <pre>
* CheckDigit routine = new ModulusTenCheckDigit(new int[] { 1, 7, 3 }, true);
* </pre>
*
* <p>
* <b>CUSIP</b> Check Digit Routine (equivalent of {@link CUSIPCheckDigit}).
* Weighting factors are <code>[1, 2]</code> applied from right to left and the
* digits of the <i>weighted value</i> are summed.
*
* <pre>
* CheckDigit routine = new ModulusTenCheckDigit(new int[] { 1, 2 }, true, true);
* </pre>
*
* <p>
* <b>EAN-13 / UPC</b> Check Digit Routine (equivalent of
* {@link EAN13CheckDigit}). Weighting factors are <code>[1, 3]</code> applied
* from right to left.
*
* <pre>
* CheckDigit routine = new ModulusTenCheckDigit(new int[] { 1, 3 }, true);
* </pre>
*
* <p>
* <b>Luhn</b> Check Digit Routine (equivalent of {@link LuhnCheckDigit}).
* Weighting factors are <code>[1, 2]</code> applied from right to left and the
* digits of the <i>weighted value</i> are summed.
*
* <pre>
* CheckDigit routine = new ModulusTenCheckDigit(new int[] { 1, 2 }, true, true);
* </pre>
*
* <p>
* <b>SEDOL</b> Check Digit Routine (equivalent of {@link SedolCheckDigit}).
* Weighting factors are <code>[1, 3, 1, 7, 3, 9, 1]</code> applied from left to
* right.
*
* <pre>
* CheckDigit routine = new ModulusTenCheckDigit(new int[] { 1, 3, 1, 7, 3, 9, 1 });
* </pre>
*
* @since 1.6
*/
public final class ModulusTenCheckDigit extends ModulusCheckDigit {
private static final long serialVersionUID = -3752929983453368497L;
/**
* The weighted values to apply based on the character position
*/
private final int[] postitionWeight;
/**
* {@code true} if use positionWeights from right to left
*/
private final boolean useRightPos;
/**
* {@code true} if sum the digits of the weighted value
*/
private final boolean sumWeightedDigits;
/**
* Constructs a modulus 10 Check Digit routine with the specified weighting
* from left to right.
*
* @param postitionWeight the weighted values to apply based on the
* character position
*/
public ModulusTenCheckDigit(final int[] postitionWeight) {
this(postitionWeight, false, false);
}
/**
* Constructs a modulus 10 Check Digit routine with the specified weighting,
* indicating whether its from the left or right.
*
* @param postitionWeight the weighted values to apply based on the
* character position
* @param useRightPos {@code true} if use positionWeights from right to
* left
*/
public ModulusTenCheckDigit(final int[] postitionWeight, final boolean useRightPos) {
this(postitionWeight, useRightPos, false);
}
/**
* Constructs a modulus 10 Check Digit routine with the specified weighting,
* indicating whether its from the left or right and whether the weighted
* digits should be summed.
*
* @param postitionWeight the weighted values to apply based on the
* character position
* @param useRightPos {@code true} if use positionWeights from right to
* left
* @param sumWeightedDigits {@code true} if sum the digits of the
* weighted value
*/
public ModulusTenCheckDigit(final int[] postitionWeight, final boolean useRightPos, final boolean sumWeightedDigits) {
this.postitionWeight = Arrays.copyOf(postitionWeight, postitionWeight.length);
this.useRightPos = useRightPos;
this.sumWeightedDigits = sumWeightedDigits;
}
/**
* Validate a modulus check digit for a code.
* <p>
* Note: assumes last digit is the check digit
*
* @param code The code to validate
* @return {@code true} if the check digit is valid, otherwise
* {@code false}
*/
@Override
public boolean isValid(final String code) {
if (GenericValidator.isBlankOrNull(code)) {
return false;
}
if (!Character.isDigit(code.charAt(code.length() - 1))) {
return false;
}
return super.isValid(code);
}
/**
* Convert a character at a specified position to an integer value.
* <p>
* <b>Note:</b> this implementation only handlers values that
* Character.getNumericValue(char) returns a non-negative number.
*
* @param character The character to convert
* @param leftPos The position of the character in the code, counting from
* left to right (for identifying the position in the string)
* @param rightPos The position of the character in the code, counting from
* right to left (not used here)
* @return The integer value of the character
* @throws CheckDigitException if Character.getNumericValue(char) returns a
* negative number
*/
@Override
protected int toInt(final char character, final int leftPos, final int rightPos) throws CheckDigitException {
final int num = Character.getNumericValue(character);
if (num < 0) {
throw new CheckDigitException("Invalid Character[" + leftPos + "] = '" + character + "'");
}
return num;
}
/**
* Return a string representation of this implementation.
*
* @return a string representation
*/
@Override
public String toString() {
return getClass().getSimpleName() + "[postitionWeight=" + Arrays.toString(postitionWeight) + ", useRightPos="
+ useRightPos + ", sumWeightedDigits=" + sumWeightedDigits + "]";
}
/**
* Calculates the <i>weighted</i> value of a character in the code at a
* specified position.
*
* @param charValue The numeric value of the character.
* @param leftPos The position of the character in the code, counting from
* left to right
* @param rightPos The position of the character in the code, counting from
* right to left
* @return The weighted value of the character.
*/
@Override
protected int weightedValue(final int charValue, final int leftPos, final int rightPos) {
final int pos = useRightPos ? rightPos : leftPos;
final int weight = postitionWeight[(pos - 1) % postitionWeight.length];
int weightedValue = charValue * weight;
if (sumWeightedDigits) {
weightedValue = sumDigits(weightedValue);
}
return weightedValue;
}
}