001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.validator.routines;
018    
019    import java.text.DecimalFormat;
020    import java.text.Format;
021    import java.math.BigDecimal;
022    
023    /**
024     * <p><b>Percentage Validation</b> and Conversion routines (<code>java.math.BigDecimal</code>).</p>
025     * 
026     * <p>This is one implementation of a percent validator that has the following features:</p>
027     *    <ul>
028     *       <li>It is <i>lenient</i> about the the presence of the <i>percent symbol</i></li>
029     *       <li>It converts the percent to a <code>java.math.BigDecimal</code></li>
030     *    </ul>
031     * 
032     * <p>However any of the <i>number</i> validators can be used for <i>percent</i> validation.
033     *    For example, if you wanted a <i>percent</i> validator that converts to a
034     *    <code>java.lang.Float</code> then you can simply instantiate an
035     *    <code>FloatValidator</code> with the appropriate <i>format type</i>:</p>
036     *    
037     *    <p><code>... = new FloatValidator(false, FloatValidator.PERCENT_FORMAT);</code></p>
038     *
039     * <p>Pick the appropriate validator, depending on the type (i.e Float, Double or BigDecimal)
040     *    you want the percent converted to. Please note, it makes no sense to use
041     *    one of the validators that doesn't handle fractions (i.e. byte, short, integer, long
042     *    and BigInteger) since percentages are converted to fractions (i.e <code>50%</code> is
043     *    converted to <code>0.5</code>).</p>
044     *
045     * @version $Revision: 493905 $ $Date: 2007-01-08 03:11:38 +0100 (Mo, 08. Jan 2007) $
046     * @since Validator 1.3.0
047     */
048    public class PercentValidator extends BigDecimalValidator {
049    
050        private static final PercentValidator VALIDATOR = new PercentValidator();
051    
052        /** DecimalFormat's percent (thousand multiplier) symbol */
053        private static final char PERCENT_SYMBOL = '%';
054    
055        private static final BigDecimal POINT_ZERO_ONE = new BigDecimal("0.01");
056    
057        /**
058         * Return a singleton instance of this validator.
059         * @return A singleton instance of the PercentValidator.
060         */
061        public static BigDecimalValidator getInstance() {
062            return VALIDATOR;
063        }
064    
065        /**
066         * Construct a <i>strict</i> instance.
067         */
068        public PercentValidator() {
069            this(true);
070        }
071    
072        /**
073         * Construct an instance with the specified strict setting.
074         * 
075         * @param strict <code>true</code> if strict 
076         *        <code>Format</code> parsing should be used.
077         */
078        public PercentValidator(boolean strict) {
079            super(strict, PERCENT_FORMAT, true);
080        }
081    
082        /**
083         * <p>Parse the value with the specified <code>Format</code>.</p>
084         * 
085         * <p>This implementation is lenient whether the currency symbol
086         *    is present or not. The default <code>NumberFormat</code>
087         *    behaviour is for the parsing to "fail" if the currency
088         *    symbol is missing. This method re-parses with a format
089         *    without the currency symbol if it fails initially.</p>
090         * 
091         * @param value The value to be parsed.
092         * @param formatter The Format to parse the value with.
093         * @return The parsed value if valid or <code>null</code> if invalid.
094         */
095        protected Object parse(String value, Format formatter) {
096    
097            // Initial parse of the value
098            BigDecimal parsedValue = (BigDecimal)super.parse(value, formatter);
099            if (parsedValue != null || !(formatter instanceof DecimalFormat)) {
100                return parsedValue;
101            }
102    
103            // Re-parse using a pattern without the percent symbol
104            DecimalFormat decimalFormat = (DecimalFormat)formatter;
105            String pattern = decimalFormat.toPattern();
106            if (pattern.indexOf(PERCENT_SYMBOL) >= 0) {
107                StringBuffer buffer = new StringBuffer(pattern.length());
108                for (int i = 0; i < pattern.length(); i++) {
109                    if (pattern.charAt(i) != PERCENT_SYMBOL) {
110                        buffer.append(pattern.charAt(i));
111                    }
112                }
113                decimalFormat.applyPattern(buffer.toString());
114                parsedValue = (BigDecimal)super.parse(value, decimalFormat);
115                
116                // If parsed OK, divide by 100 to get percent
117                if (parsedValue != null) {
118                    parsedValue = parsedValue.multiply(POINT_ZERO_ONE);
119                }
120                
121            }
122            return parsedValue;
123        }
124    }