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From rdon...@apache.org
Subject cvs commit: jakarta-commons/beanutils/src/java/org/apache/commons/beanutils BeanPropertyValueEqualsPredicate.java
Date Thu, 28 Aug 2003 20:59:55 GMT
rdonkin     2003/08/28 13:59:55

  Added:       beanutils/src/java/org/apache/commons/beanutils
                        BeanPropertyValueEqualsPredicate.java
  Log:
  A Predicate (thanks commons-collections) that evaludates property values. Submitted by Norm
Deane
  
  Revision  Changes    Path
  1.1                  jakarta-commons/beanutils/src/java/org/apache/commons/beanutils/BeanPropertyValueEqualsPredicate.java
  
  Index: BeanPropertyValueEqualsPredicate.java
  ===================================================================
  /*
   * $Header: /home/cvs/jakarta-commons/beanutils/src/java/org/apache/commons/beanutils/BeanPropertyValueEqualsPredicate.java,v
1.1 2003/08/28 20:59:55 rdonkin Exp $
   * $Revision: 1.1 $
   * $Date: 2003/08/28 20:59:55 $
   *
   * ====================================================================
   *
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Group.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.commons.beanutils;
  
  import org.apache.commons.collections.Predicate;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import java.lang.reflect.InvocationTargetException;
  
  
  /**
   * <p><code>Predicate</code> that evaluates a property value against a
specified value.</p>
   * <p>
   * An implementation of <code>org.apache.commons.collections.Predicate</code>
that evaluates a
   * property value on the object provided against a specified value and returns <code>true</code>
   * if equal; <code>false</code> otherwise.
   * The <code>BeanPropertyValueEqualsPredicate</code> constructor takes two parameters
which
   * determine what property will be evaluated on the target object and what its expected
value should
   * be.
   * <dl>
   *    <dt>
   *       <strong><code><pre>public BeanPropertyValueEqualsPredicate( String
propertyName, Object propertyValue )</pre></code></strong>
   *    </dt>
   *    <dd>
   *       Will create a <code>Predicate</code> that will evaluate the target
object and return
   *       <code>true</code> if the property specified by <code>propertyName</code>
has a value which
   *       is equal to the the value specified by <code>propertyValue</code>.
Or return
   *       <code>false</code> otherwise.
   *    </dd>
   * </dl>
   * </p>
   * <p>
   * <strong>Note:</strong> Property names can be a simple, nested, indexed, or
mapped property as defined by
   * <code>org.apache.commons.beanutils.PropertyUtils</code>.  If any object in
the property path
   * specified by <code>propertyName</code> is <code>null</code> then
the outcome is based on the
   * value of the <code>ignoreNull</code> attribute.
   * </p>
   * <p>
   * A typical usage might look like:
   * <code><pre>
   * // create the closure
   * BeanPropertyValueEqualsPredicate predicate =
   *    new BeanPropertyValueEqualsPredicate( "activeEmployee", Boolean.FALSE );
   *
   * // filter the Collection
   * CollectionUtils.filter( peopleCollection, predicate );
   * </pre></code>
   * </p>
   * <p>
   * This would take a <code>Collection</code> of person objects and filter out
any people whose
   * <code>activeEmployee</code> property is <code>false</code>. Assuming...
   * <ul>
   *    <li>
   *       The top level object in the <code>peeopleCollection</code> is an object
which represents a
   *       person.
   *    </li>
   *    <li>
   *       The person object has a <code>getActiveEmployee()</code> method which
returns
   *       the boolean value for the object's <code>activeEmployee</code> property.
   *    </li>
   * </ul>
   * </p>
   * <p>
   * Another typical usage might look like:
   * <code><pre>
   * // create the closure
   * BeanPropertyValueEqualsPredicate predicate =
   *    new BeanPropertyValueEqualsPredicate( "personId", "456-12-1234" );
   *
   * // search the Collection
   * CollectionUtils.find( peopleCollection, predicate );
   * </pre><code>
   * </p>
   * <p>
   * This would search a <code>Collection</code> of person objects and return
the first object whose
   * <code>personId</code> property value equals <code>456-12-1234</code>.
Assuming...
   * <ul>
   *    <li>
   *       The top level object in the <code>peeopleCollection</code> is an object
which represents a
   *       person.
   *    </li>
   *    <li>
   *       The person object has a <code>getPersonId()</code> method which returns
   *       the value for the object's <code>personId</code> property.
   *    </li>
   * </ul>
   * </p>
   *
   * @author Norm Deane
   * @see org.apache.commons.beanutils.PropertyUtils
   * @see org.apache.commons.collections.Predicate
   */
  public class BeanPropertyValueEqualsPredicate implements Predicate {
     
      /** For logging. */
      private final Log log = LogFactory.getLog(this.getClass());
  
      /**
       * The name of the property which will be evaluated when this <code>Predicate</code>
is executed.
       */
      private String propertyName;
  
      /**
       * The value that the property specified by <code>propertyName</code>
       * will be compared to when this <code>Predicate</code> executes.
       */
      private Object propertyValue;
  
      /**
       * <p>Should <code>null</code> objects in the property path be ignored?</p>
       * <p>
       * Determines whether <code>null</code> objects in the property path will
genenerate an
       * <code>IllegalArgumentException</code> or not. If set to <code>true</code>
then if any objects
       * in the property path evaluate to <code>null</code> then the
       * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code>
will be logged but
       * not rethrown and <code>false</code> will be returned.  If set to <code>false</code>
then if
       * any objects in the property path evaluate to <code>null</code> then the
       * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code>
will be logged and
       * rethrown.
       * </p>
       */
      private boolean ignoreNull;
  
      /**
       * Constructor which takes the name of the property, its expected value to be used in
evaluation,
       * and assumes <code>ignoreNull</code> to be <code>false</code>.
       *
       * @param propertyName The name of the property that will be evaluated against the expected
value.
       * @param propertyValue The value to use in object evaluation.
       * @throws IllegalArgumentException If the property name provided is null or empty.
       */
      public BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue) {
          this(propertyName, propertyValue, false);
      }
  
      /**
       * Constructor which takes the name of the property, its expected value
       * to be used in evaluation, and a boolean which determines whether <code>null</code>
objects in
       * the property path will genenerate an <code>IllegalArgumentException</code>
or not.
       *
       * @param propertyName The name of the property that will be evaluated against the expected
value.
       * @param propertyValue The value to use in object evaluation.
       * @param ignoreNull Determines whether <code>null</code> objects in the
property path will
       * genenerate an <code>IllegalArgumentException</code> or not.
       * @throws IllegalArgumentException If the property name provided is null or empty.
       */
      public BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue, boolean
ignoreNull) {
          super();
  
          if ((propertyName != null) && (propertyName.length() > 0)) {
              this.propertyName = propertyName;
              this.propertyValue = propertyValue;
              this.ignoreNull = ignoreNull;
          } else {
              throw new IllegalArgumentException("propertyName cannot be null or empty");
          }
      }
  
      /**
       * Evaulates the object provided against the criteria specified when this
       * <code>BeanPropertyValueEqualsPredicate</code> was constructed.  Equality
is based on
       * either reference or logical equality as defined by the property object's equals method.
If
       * any object in the property path leading up to the target property is <code>null</code>
then
       * the outcome will be based on the value of the <code>ignoreNull</code>
attribute. By default,
       * <code>ignoreNull</code> is <code>false</code> and would result
in an
       * <code>IllegalArgumentException</code> if an object in the property path
leading up to the
       * target property is <code>null</code>.
       *
       * @param object The object to be evaluated.
       * @return True if the object provided meets all the criteria for this <code>Predicate</code>;
       * false otherwise.
       * @throws IllegalArgumentException If an IllegalAccessException, InvocationTargetException,
or
       * NoSuchMethodException is thrown when trying to access the property specified on the
object
       * provided. Or if an object in the property path provided is <code>null</code>
and
       * <code>ignoreNull</code> is set to <code>false</code>.
       */
      public boolean evaluate(Object object) {
         
          boolean evaluation = false;
  
          try {
              evaluation = evaluateValue(propertyValue,
                      PropertyUtils.getProperty(object, propertyName));
          } catch (IllegalArgumentException e) {
              final String errorMsg = "Problem during evaluation. Null value encountered in
property path...";
  
              if (ignoreNull) {
                  log.warn("WARNING: " + errorMsg, e);
              } else {
                  log.error("ERROR: " + errorMsg, e);
                  throw e;
              }
          } catch (IllegalAccessException e) {
              final String errorMsg = "Unable to access the property provided.";
              log.error(errorMsg, e);
              throw new IllegalArgumentException(errorMsg);
          } catch (InvocationTargetException e) {
              final String errorMsg = "Exception occurred in property's getter";
              log.error(errorMsg, e);
              throw new IllegalArgumentException(errorMsg);
          } catch (NoSuchMethodException e) {
              final String errorMsg = "Property not found.";
              log.error(errorMsg, e);
              throw new IllegalArgumentException(errorMsg);
          }
  
          return evaluation;
      }
  
      /**
       * Utility method which evaluates whether the actual property value equals the expected
property
       * value.
       *
       * @param expected The expected value.
       * @param actual The actual value.
       * @return True if they are equal; false otherwise.
       */
      private boolean evaluateValue(Object expected, Object actual) {
          return (expected == actual) || ((expected != null) && expected.equals(actual));
      }
  
      /**
       * Returns the name of the property which will be evaluated when this <code>Predicate</code>
is
       * executed.
       *
       * @return The name of the property which will be evaluated when this <code>Predicate</code>
is
       * executed.
       */
      public String getPropertyName() {
          return propertyName;
      }
  
      /**
       * Returns the value that the property specified by <code>propertyName</code>
will be compared to
       * when this <code>Predicate</code> executes.
       *
       * @return The value that the property specified by <code>propertyName</code>
will be compared to
       * when this <code>Predicate</code> executes.
       */
      public Object getPropertyValue() {
          return propertyValue;
      }
  
      /**
       * Returns the flag which determines whether <code>null</code> objects in
the property path will
       * genenerate an <code>IllegalArgumentException</code> or not. If set to
<code>true</code> then
       * if any objects in the property path evaluate to <code>null</code> then
the
       * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code>
will be logged but
       * not rethrown and <code>false</code> will be returned.  If set to <code>false</code>
then if
       * any objects in the property path evaluate to <code>null</code> then the
       * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code>
will be logged and
       * rethrown.
       *
       * @return The flag which determines whether <code>null</code> objects in
the property path will
       * genenerate an <code>IllegalArgumentException</code> or not.
       */
      public boolean isIgnoreNull() {
          return ignoreNull;
      }
  }
  
  
  

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