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Posted to dev@commons.apache.org by rd...@apache.org on 2003/08/28 22:59:55 UTC
cvs commit: jakarta-commons/beanutils/src/java/org/apache/commons/beanutils BeanPropertyValueEqualsPredicate.java
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.
*
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* modification, are permitted provided that the following conditions
* are met:
*
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* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowlegement may appear in the software itself,
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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;
}
}