Source code

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}