Java tutorial
/* * 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.beanutils; import org.apache.commons.collections.Closure; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.lang.reflect.InvocationTargetException; /** * <p><code>Closure</code> that sets a property.</p> * <p> * An implementation of <code>org.apache.commons.collections.Closure</code> that updates * a specified property on the object provided with a specified value. * The <code>BeanPropertyValueChangeClosure</code> constructor takes two parameters which determine * what property will be updated and with what value. * <dl> * <dt> * <b><code> * <pre>public BeanPropertyValueChangeClosure( String propertyName, Object propertyValue )</pre> * </code></b> * </dt> * <dd> * Will create a <code>Closure</code> that will update an object by setting the property * specified by <code>propertyName</code> to the value specified by <code>propertyValue</code>. * </dd> * </dl> * * <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/> * A typical usage might look like: * <code><pre> * // create the closure * BeanPropertyValueChangeClosure closure = * new BeanPropertyValueChangeClosure( "activeEmployee", Boolean.TRUE ); * * // update the Collection * CollectionUtils.forAllDo( peopleCollection, closure ); * </pre></code> * <p/> * * This would take a <code>Collection</code> of person objects and update the * <code>activeEmployee</code> property of each object in the <code>Collection</code> to * <code>true</code>. Assuming... * <ul> * <li> * The top level object in the <code>peopleCollection</code> is an object which represents a * person. * </li> * <li> * The person object has a <code>setActiveEmployee( boolean )</code> method which updates * the value for the object's <code>activeEmployee</code> property. * </li> * </ul> * * @author Norm Deane * @see org.apache.commons.beanutils.PropertyUtils * @see org.apache.commons.collections.Closure */ public class BeanPropertyValueChangeClosure implements Closure { /** For logging. */ private final Log log = LogFactory.getLog(this.getClass()); /** * The name of the property which will be updated when this <code>Closure</code> executes. */ private String propertyName; /** * The value that the property specified by <code>propertyName</code> * will be updated to when this <code>Closure</code> executes. */ private Object propertyValue; /** * 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 leading up to the target property evaluate to <code>null</code> then the * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged but * not rethrown. If set to <code>false</code> then if any objects in the property path leading * up to the target property evaluate to <code>null</code> then the * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged and * rethrown. */ private boolean ignoreNull; /** * Constructor which takes the name of the property to be changed, the new value to set * the property to, and assumes <code>ignoreNull</code> to be <code>false</code>. * * @param propertyName The name of the property that will be updated with the value specified by * <code>propertyValue</code>. * @param propertyValue The value that <code>propertyName</code> will be set to on the target * object. * @throws IllegalArgumentException If the propertyName provided is null or empty. */ public BeanPropertyValueChangeClosure(String propertyName, Object propertyValue) { this(propertyName, propertyValue, false); } /** * Constructor which takes the name of the property to be changed, the new value to set * the property to 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 updated with the value specified by * <code>propertyValue</code>. * @param propertyValue The value that <code>propertyName</code> will be set to on the target * object. * @param ignoreNull Determines whether <code>null</code> objects in the property path will * genenerate an <code>IllegalArgumentException</code> or not. * @throws IllegalArgumentException If the propertyName provided is null or empty. */ public BeanPropertyValueChangeClosure(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"); } } /** * Updates the target object provided using the property update criteria provided when this * <code>BeanPropertyValueChangeClosure</code> was constructed. 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 updated. * @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 void execute(Object object) { try { PropertyUtils.setProperty(object, propertyName, propertyValue); } catch (IllegalArgumentException e) { final String errorMsg = "Unable to execute Closure. Null value encountered in property path..."; if (ignoreNull) { log.warn("WARNING: " + errorMsg + e); } else { IllegalArgumentException iae = new IllegalArgumentException(errorMsg); if (!BeanUtils.initCause(iae, e)) { log.error(errorMsg, e); } throw iae; } } catch (IllegalAccessException e) { final String errorMsg = "Unable to access the property provided."; IllegalArgumentException iae = new IllegalArgumentException(errorMsg); if (!BeanUtils.initCause(iae, e)) { log.error(errorMsg, e); } throw iae; } catch (InvocationTargetException e) { final String errorMsg = "Exception occurred in property's getter"; IllegalArgumentException iae = new IllegalArgumentException(errorMsg); if (!BeanUtils.initCause(iae, e)) { log.error(errorMsg, e); } throw iae; } catch (NoSuchMethodException e) { final String errorMsg = "Property not found"; IllegalArgumentException iae = new IllegalArgumentException(errorMsg); if (!BeanUtils.initCause(iae, e)) { log.error(errorMsg, e); } throw iae; } } /** * Returns the name of the property which will be updated when this <code>Closure</code> executes. * * @return The name of the property which will be updated when this <code>Closure</code> executes. */ public String getPropertyName() { return propertyName; } /** * Returns the value that the property specified by <code>propertyName</code> * will be updated to when this <code>Closure</code> executes. * * @return The value that the property specified by <code>propertyName</code> * will be updated to when this <code>Closure</code> executes. */ public Object getPropertyValue() { return propertyValue; } /** * Returns the flag that 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 leading up to the target property evaluate to * <code>null</code> then the <code>IllegalArgumentException</code> throw by * <code>PropertyUtils</code> will be logged but not rethrown. If set to <code>false</code> then * if any objects in the property path leading up to the target property evaluate to * <code>null</code> then the <code>IllegalArgumentException</code> throw by * <code>PropertyUtils</code> will be logged and rethrown. * * @return The flag that determines whether <code>null</code> objects in the property path will * genenerate an <code>IllegalArgumentException</code> or not. */ public boolean isIgnoreNull() { return ignoreNull; } }