BeanPropertyValueEqualsPredicate.java
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.beanutils2;
import java.lang.reflect.InvocationTargetException;
import java.util.Objects;
import java.util.function.Predicate;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* <p>
* {@code Predicate} that evaluates a property value against a specified value.
* </p>
* <p>
* An implementation of {@link java.util.function.Predicate} that evaluates a property value on the object provided against a specified value and returns
* {@code true} if equal; {@code false} otherwise. The {@code BeanPropertyValueEqualsPredicate} constructor takes two parameters which determine what property
* will be evaluated on the target object and what its expected value should be.
* </p>
* <dl>
* <dt><strong> {@code public BeanPropertyValueEqualsPredicate( String propertyName, Object propertyValue )} </strong></dt>
* <dd>Will create a {@code Predicate} that will evaluate the target object and return
* {@code true</code> if the property specified by <code>propertyName} has a value which
* is equal to the value specified by {@code propertyValue}. Or return
* {@code false} otherwise.
* </dd>
* </dl>
* <p>
* <strong>Note:</strong> Property names can be a simple, nested, indexed, or mapped property as defined by
* {@code org.apache.commons.beanutils2.PropertyUtils}. If any object in the property path
* specified by {@code propertyName</code> is <code>null} then the outcome is based on the
* value of the {@code ignoreNull} attribute.
* </p>
* <p>
* A typical usage might look like:
* </p>
* <pre>{@code
* // create the closure
* BeanPropertyValueEqualsPredicate predicate =
* new BeanPropertyValueEqualsPredicate( "activeEmployee", Boolean.FALSE );
*
* // filter the Collection
* CollectionUtils.filter( peopleCollection, predicate );
* }</pre>
* <p>
* This would take a {@code Collection} of person objects and filter out any people whose
* {@code activeEmployee</code> property is <code>false}. Assuming...
* </p>
* <ul>
* <li>
* The top level object in the {@code peopleCollection} is an object which represents a
* person.
* </li>
* <li>
* The person object has a {@code getActiveEmployee()} method which returns
* the boolean value for the object's {@code activeEmployee} property.
* </li>
* </ul>
* <p>
* Another typical usage might look like:
* </p>
* <pre>{@code
* // create the closure
* BeanPropertyValueEqualsPredicate predicate =
* new BeanPropertyValueEqualsPredicate( "personId", "456-12-1234" );
*
* // search the Collection
* CollectionUtils.find( peopleCollection, predicate );
* }</pre>
* <p>
* This would search a {@code Collection} of person objects and return the first object whose
* {@code personId</code> property value equals <code>456-12-1234}. Assuming...
* </p>
* <ul>
* <li>The top level object in the {@code peopleCollection} is an object which represents a person.</li>
* <li>The person object has a {@code getPersonId()} method which returns the value for the object's {@code personId} property.</li>
* </ul>
*
* @param <T> The type of the input to the predicate.
* @param <V> The property value type.
* @see org.apache.commons.beanutils2.PropertyUtils
* @see java.util.function.Predicate
*/
public class BeanPropertyValueEqualsPredicate<T, V> implements Predicate<T> {
/** For logging. Each subclass gets its own log instance. */
private final Log log = LogFactory.getLog(this.getClass());
/**
* The name of the property which will be evaluated when this {@code Predicate} is executed.
*/
private final String propertyName;
/**
* The value that the property specified by {@code propertyName} will be compared to when this {@code Predicate} executes.
*/
private final V propertyValue;
/**
* <p>
* Should {@code null} objects in the property path be ignored?
* </p>
* <p>
* Determines whether {@code null} objects in the property path will generate an
* {@code IllegalArgumentException</code> or not. If set to <code>true} then if any objects
* in the property path evaluate to {@code null} then the
* {@code IllegalArgumentException</code> throw by <code>PropertyUtils} will be logged but
* not re-thrown and {@code false</code> will be returned. If set to <code>false} then if
* any objects in the property path evaluate to {@code null} then the
* {@code IllegalArgumentException</code> throw by <code>PropertyUtils} will be logged and re-thrown.
* </p>
*/
private final 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}.
*
* @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(final String propertyName, final V 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}
* objects in the property path will generate an {@code IllegalArgumentException} 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} objects in the property path will generate an {@code IllegalArgumentException} or not.
* @throws IllegalArgumentException If the property name provided is null or empty.
*/
public BeanPropertyValueEqualsPredicate(final String propertyName, final V propertyValue, final boolean ignoreNull) {
if (propertyName == null || propertyName.isEmpty()) {
throw new IllegalArgumentException("propertyName cannot be null or empty");
}
this.propertyName = propertyName;
this.propertyValue = propertyValue;
this.ignoreNull = ignoreNull;
}
/**
* 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.
*/
protected boolean evaluateValue(final V expected, final Object actual) {
return Objects.equals(expected, actual);
}
/**
* Returns the name of the property which will be evaluated when this {@code Predicate} is executed.
*
* @return The name of the property which will be evaluated when this {@code Predicate} is executed.
*/
public String getPropertyName() {
return propertyName;
}
/**
* Returns the value that the property specified by {@code propertyName} will be compared to when this {@code Predicate} executes.
*
* @return The value that the property specified by {@code propertyName} will be compared to when this {@code Predicate} executes.
*/
public V getPropertyValue() {
return propertyValue;
}
/**
* Returns the flag which determines whether {@code null} objects in the property path will generate an
* {@code IllegalArgumentException</code> or not. If set to <code>true} then
* if any objects in the property path evaluate to {@code null} then the
* {@code IllegalArgumentException</code> throw by <code>PropertyUtils} will be logged but
* not re-thrown and {@code false</code> will be returned. If set to <code>false} then if
* any objects in the property path evaluate to {@code null} then the
* {@code IllegalArgumentException</code> throw by <code>PropertyUtils} will be logged and re-thrown.
*
* @return The flag which determines whether {@code null} objects in the property path will generate an {@code IllegalArgumentException} or not.
*/
public boolean isIgnoreNull() {
return ignoreNull;
}
/**
* Evaluates the object provided against the criteria specified when this {@code BeanPropertyValueEqualsPredicate} 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} then the outcome will be based on the value of the {@code ignoreNull} attribute. By default,
* {@code ignoreNull</code> is <code>false} and would result in an
* {@code IllegalArgumentException} if an object in the property path leading up to the
* target property is {@code null}.
*
* @param object The object to be evaluated.
* @return True if the object provided meets all the criteria for this {@code Predicate};
* 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} and
* {@code ignoreNull</code> is set to <code>false}.
*/
@Override
public boolean test(final T object) {
boolean evaluation = false;
try {
evaluation = evaluateValue(propertyValue, PropertyUtils.getProperty(object, propertyName));
} catch (final IllegalArgumentException e) {
final String errorMsg = "Problem during evaluation. Null value encountered in property path...";
if (!ignoreNull) {
throw new IllegalArgumentException(errorMsg, e);
}
log.warn(errorMsg, e);
} catch (final IllegalAccessException e) {
final String errorMsg = "Unable to access the property provided.";
throw new IllegalArgumentException(errorMsg, e);
} catch (final InvocationTargetException e) {
final String errorMsg = "Exception occurred in property's getter";
throw new IllegalArgumentException(errorMsg, e);
} catch (final NoSuchMethodException e) {
final String errorMsg = "Property not found.";
throw new IllegalArgumentException(errorMsg, e);
}
return evaluation;
}
}