    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
    018package org.apache.commons.beanutils;
    019
    020import java.lang.reflect.InvocationTargetException;
    021
    022import org.apache.commons.collections.Predicate;
    023import org.apache.commons.logging.Log;
    024import org.apache.commons.logging.LogFactory;
    025
    026
    027/**
    028 * <p><code>Predicate</code> that evaluates a property value against a specified value.</p>
    029 * <p>
    030 * An implementation of <code>org.apache.commons.collections.Predicate</code> that evaluates a
    031 * property value on the object provided against a specified value and returns <code>true</code>
    032 * if equal; <code>false</code> otherwise.
    033 * The <code>BeanPropertyValueEqualsPredicate</code> constructor takes two parameters which
    034 * determine what property will be evaluated on the target object and what its expected value should
    035 * be.
    036 * <dl>
    037 *    <dt>
    038 *       <strong><code>
    039 *           <pre>public BeanPropertyValueEqualsPredicate( String propertyName, Object propertyValue )</pre>
    040 *       </code></strong>
    041 *    </dt>
    042 *    <dd>
    043 *       Will create a <code>Predicate</code> that will evaluate the target object and return
    044 *       <code>true</code> if the property specified by <code>propertyName</code> has a value which
    045 *       is equal to the the value specified by <code>propertyValue</code>. Or return
    046 *       <code>false</code> otherwise.
    047 *    </dd>
    048 * </dl>
    049 * </p>
    050 * <p>
    051 * <strong>Note:</strong> Property names can be a simple, nested, indexed, or mapped property as defined by
    052 * <code>org.apache.commons.beanutils.PropertyUtils</code>.  If any object in the property path
    053 * specified by <code>propertyName</code> is <code>null</code> then the outcome is based on the
    054 * value of the <code>ignoreNull</code> attribute.
    055 * </p>
    056 * <p>
    057 * A typical usage might look like:
    058 * <code><pre>
    059 * // create the closure
    060 * BeanPropertyValueEqualsPredicate predicate =
    061 *    new BeanPropertyValueEqualsPredicate( "activeEmployee", Boolean.FALSE );
    062 *
    063 * // filter the Collection
    064 * CollectionUtils.filter( peopleCollection, predicate );
    065 * </pre></code>
    066 * </p>
    067 * <p>
    068 * This would take a <code>Collection</code> of person objects and filter out any people whose
    069 * <code>activeEmployee</code> property is <code>false</code>. Assuming...
    070 * <ul>
    071 *    <li>
    072 *       The top level object in the <code>peeopleCollection</code> is an object which represents a
    073 *       person.
    074 *    </li>
    075 *    <li>
    076 *       The person object has a <code>getActiveEmployee()</code> method which returns
    077 *       the boolean value for the object's <code>activeEmployee</code> property.
    078 *    </li>
    079 * </ul>
    080 * </p>
    081 * <p>
    082 * Another typical usage might look like:
    083 * <code><pre>
    084 * // create the closure
    085 * BeanPropertyValueEqualsPredicate predicate =
    086 *    new BeanPropertyValueEqualsPredicate( "personId", "456-12-1234" );
    087 *
    088 * // search the Collection
    089 * CollectionUtils.find( peopleCollection, predicate );
    090 * </pre></code>
    091 * </p>
    092 * <p>
    093 * This would search a <code>Collection</code> of person objects and return the first object whose
    094 * <code>personId</code> property value equals <code>456-12-1234</code>. Assuming...
    095 * <ul>
    096 *    <li>
    097 *       The top level object in the <code>peeopleCollection</code> is an object which represents a
    098 *       person.
    099 *    </li>
    100 *    <li>
    101 *       The person object has a <code>getPersonId()</code> method which returns
    102 *       the value for the object's <code>personId</code> property.
    103 *    </li>
    104 * </ul>
    105 * </p>
    106 *
    107 * @version $Id$
    108 * @see org.apache.commons.beanutils.PropertyUtils
    109 * @see org.apache.commons.collections.Predicate
    110 */
    111public class BeanPropertyValueEqualsPredicate implements Predicate {
    112
    113    /** For logging. */
    114    private final Log log = LogFactory.getLog(this.getClass());
    115
    116    /**
    117     * The name of the property which will be evaluated when this <code>Predicate</code> is executed.
    118     */
    119    private String propertyName;
    120
    121    /**
    122     * The value that the property specified by <code>propertyName</code>
    123     * will be compared to when this <code>Predicate</code> executes.
    124     */
    125    private Object propertyValue;
    126
    127    /**
    128     * <p>Should <code>null</code> objects in the property path be ignored?</p>
    129     * <p>
    130     * Determines whether <code>null</code> objects in the property path will genenerate an
    131     * <code>IllegalArgumentException</code> or not. If set to <code>true</code> then if any objects
    132     * in the property path evaluate to <code>null</code> then the
    133     * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged but
    134     * not rethrown and <code>false</code> will be returned.  If set to <code>false</code> then if
    135     * any objects in the property path evaluate to <code>null</code> then the
    136     * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged and
    137     * rethrown.
    138     * </p>
    139     */
    140    private boolean ignoreNull;
    141
    142    /**
    143     * Constructor which takes the name of the property, its expected value to be used in evaluation,
    144     * and assumes <code>ignoreNull</code> to be <code>false</code>.
    145     *
    146     * @param propertyName The name of the property that will be evaluated against the expected value.
    147     * @param propertyValue The value to use in object evaluation.
    148     * @throws IllegalArgumentException If the property name provided is null or empty.
    149     */
    150    public BeanPropertyValueEqualsPredicate(final String propertyName, final Object propertyValue) {
    151        this(propertyName, propertyValue, false);
    152    }
    153
    154    /**
    155     * Constructor which takes the name of the property, its expected value
    156     * to be used in evaluation, and a boolean which determines whether <code>null</code> objects in
    157     * the property path will genenerate an <code>IllegalArgumentException</code> or not.
    158     *
    159     * @param propertyName The name of the property that will be evaluated against the expected value.
    160     * @param propertyValue The value to use in object evaluation.
    161     * @param ignoreNull Determines whether <code>null</code> objects in the property path will
    162     * genenerate an <code>IllegalArgumentException</code> or not.
    163     * @throws IllegalArgumentException If the property name provided is null or empty.
    164     */
    165    public BeanPropertyValueEqualsPredicate(final String propertyName, final Object propertyValue, final boolean ignoreNull) {
    166        super();
    167
    168        if ((propertyName != null) && (propertyName.length() > 0)) {
    169            this.propertyName = propertyName;
    170            this.propertyValue = propertyValue;
    171            this.ignoreNull = ignoreNull;
    172        } else {
    173            throw new IllegalArgumentException("propertyName cannot be null or empty");
    174        }
    175    }
    176
    177    /**
    178     * Evaulates the object provided against the criteria specified when this
    179     * <code>BeanPropertyValueEqualsPredicate</code> was constructed.  Equality is based on
    180     * either reference or logical equality as defined by the property object's equals method. If
    181     * any object in the property path leading up to the target property is <code>null</code> then
    182     * the outcome will be based on the value of the <code>ignoreNull</code> attribute. By default,
    183     * <code>ignoreNull</code> is <code>false</code> and would result in an
    184     * <code>IllegalArgumentException</code> if an object in the property path leading up to the
    185     * target property is <code>null</code>.
    186     *
    187     * @param object The object to be evaluated.
    188     * @return True if the object provided meets all the criteria for this <code>Predicate</code>;
    189     * false otherwise.
    190     * @throws IllegalArgumentException If an IllegalAccessException, InvocationTargetException, or
    191     * NoSuchMethodException is thrown when trying to access the property specified on the object
    192     * provided. Or if an object in the property path provided is <code>null</code> and
    193     * <code>ignoreNull</code> is set to <code>false</code>.
    194     */
    195    public boolean evaluate(final Object object) {
    196
    197        boolean evaluation = false;
    198
    199        try {
    200            evaluation = evaluateValue(propertyValue,
    201                    PropertyUtils.getProperty(object, propertyName));
    202        } catch (final IllegalArgumentException e) {
    203            final String errorMsg = "Problem during evaluation. Null value encountered in property path...";
    204
    205            if (ignoreNull) {
    206                log.warn("WARNING: " + errorMsg + e);
    207            } else {
    208                final IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
    209                if (!BeanUtils.initCause(iae, e)) {
    210                    log.error(errorMsg, e);
    211                }
    212                throw iae;
    213            }
    214        } catch (final IllegalAccessException e) {
    215            final String errorMsg = "Unable to access the property provided.";
    216            final IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
    217            if (!BeanUtils.initCause(iae, e)) {
    218                log.error(errorMsg, e);
    219            }
    220            throw iae;
    221        } catch (final InvocationTargetException e) {
    222            final String errorMsg = "Exception occurred in property's getter";
    223            final IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
    224            if (!BeanUtils.initCause(iae, e)) {
    225                log.error(errorMsg, e);
    226            }
    227            throw iae;
    228        } catch (final NoSuchMethodException e) {
    229            final String errorMsg = "Property not found.";
    230            final IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
    231            if (!BeanUtils.initCause(iae, e)) {
    232                log.error(errorMsg, e);
    233            }
    234            throw iae;
    235        }
    236
    237        return evaluation;
    238    }
    239
    240    /**
    241     * Utility method which evaluates whether the actual property value equals the expected property
    242     * value.
    243     *
    244     * @param expected The expected value.
    245     * @param actual The actual value.
    246     * @return True if they are equal; false otherwise.
    247     */
    248    protected boolean evaluateValue(final Object expected, final Object actual) {
    249        return (expected == actual) || ((expected != null) && expected.equals(actual));
    250    }
    251
    252    /**
    253     * Returns the name of the property which will be evaluated when this <code>Predicate</code> is
    254     * executed.
    255     *
    256     * @return The name of the property which will be evaluated when this <code>Predicate</code> is
    257     * executed.
    258     */
    259    public String getPropertyName() {
    260        return propertyName;
    261    }
    262
    263    /**
    264     * Returns the value that the property specified by <code>propertyName</code> will be compared to
    265     * when this <code>Predicate</code> executes.
    266     *
    267     * @return The value that the property specified by <code>propertyName</code> will be compared to
    268     * when this <code>Predicate</code> executes.
    269     */
    270    public Object getPropertyValue() {
    271        return propertyValue;
    272    }
    273
    274    /**
    275     * Returns the flag which determines whether <code>null</code> objects in the property path will
    276     * genenerate an <code>IllegalArgumentException</code> or not. If set to <code>true</code> then
    277     * if any objects in the property path evaluate to <code>null</code> then the
    278     * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged but
    279     * not rethrown and <code>false</code> will be returned.  If set to <code>false</code> then if
    280     * any objects in the property path evaluate to <code>null</code> then the
    281     * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged and
    282     * rethrown.
    283     *
    284     * @return The flag which determines whether <code>null</code> objects in the property path will
    285     * genenerate an <code>IllegalArgumentException</code> or not.
    286     */
    287    public boolean isIgnoreNull() {
    288        return ignoreNull;
    289    }
    290}