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Commons Beanutils example source code file (BeanToPropertyValueTransformer.java)

This example Commons Beanutils source code file (BeanToPropertyValueTransformer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Beanutils tags/keywords

beantopropertyvaluetransformer, beantopropertyvaluetransformer, illegalaccessexception, illegalargumentexception, illegalargumentexception, log, no, object, object, problem, reflection, string, string, unable, warning

The Commons Beanutils BeanToPropertyValueTransformer.java source code

/*
 * 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.Transformer;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.lang.reflect.InvocationTargetException;


/**
 * <p>Transformer that outputs a property value.

* * <p>An implementation of org.apache.commons.collections.Transformer that transforms * the object provided by returning the value of a specified property of the object. The * constructor for <code>BeanToPropertyValueTransformer requires the name of the property * that will be used in the transformation. The property can be a simple, nested, indexed, or * mapped property as defined by <code>org.apache.commons.beanutils.PropertyUtils. If any * object in the property path specified by <code>propertyName is null then the * outcome is based on the value of the <code>ignoreNull attribute. * </p> * * <p> * A typical usage might look like: * <code>
 * // create the transformer
 * BeanToPropertyValueTransformer transformer = new BeanToPropertyValueTransformer( "person.address.city" );
 *
 * // transform the Collection
 * Collection peoplesCities = CollectionUtils.collect( peopleCollection, transformer );
 * </pre>
 * </p>
 *
 * <p>
 * This would take a <code>Collection of person objects and return a Collection
 * of objects which represents the cities in which each person lived. Assuming...
 * <ul>
 *    <li>
 *       The top level object in the <code>peeopleCollection is an object which represents a
 *       person.
 *    </li>
 *    <li>
 *       The person object has a <code>getAddress() method which returns an object which
 *       represents a person's address.
 *    </li>
 *    <li>
 *       The address object has a <code>getCity() method which returns an object which
 *       represents the city in which a person lives.
 *    </li>
 * </ul>
 *
 * @author Norm Deane
 * @see org.apache.commons.beanutils.PropertyUtils
 * @see org.apache.commons.collections.Transformer
 */
public class BeanToPropertyValueTransformer implements Transformer {
   
    /** For logging. */
    private final Log log = LogFactory.getLog(this.getClass());

    /** The name of the property that will be used in the transformation of the object. */
    private String propertyName;

    /**
     * <p>Should null objects on the property path throw an IllegalArgumentException?

* <p> * Determines whether <code>null objects in the property path will genenerate an * <code>IllegalArgumentException or not. If set to true then if any objects * in the property path evaluate to <code>null then the * <code>IllegalArgumentException throw by PropertyUtils will be logged but * not rethrown and <code>null will be returned. If set to false then if any * objects in the property path evaluate to <code>null then the * <code>IllegalArgumentException throw by PropertyUtils will be logged and * rethrown. * </p> */ private boolean ignoreNull; /** * Constructs a Transformer which does not ignore nulls. * Constructor which takes the name of the property that will be used in the transformation and * assumes <code>ignoreNull to be false. * * @param propertyName The name of the property that will be used in the transformation. * @throws IllegalArgumentException If the <code>propertyName is null or * empty. */ public BeanToPropertyValueTransformer(String propertyName) { this(propertyName, false); } /** * Constructs a Transformer and sets ignoreNull. * Constructor which takes the name of the property that will be used in the transformation and * a boolean which determines whether <code>null objects in the property path will * genenerate an <code>IllegalArgumentException or not. * * @param propertyName The name of the property that will be used in the transformation. * @param ignoreNull Determines whether <code>null objects in the property path will * genenerate an <code>IllegalArgumentException or not. * @throws IllegalArgumentException If the <code>propertyName is null or * empty. */ public BeanToPropertyValueTransformer(String propertyName, boolean ignoreNull) { super(); if ((propertyName != null) && (propertyName.length() > 0)) { this.propertyName = propertyName; this.ignoreNull = ignoreNull; } else { throw new IllegalArgumentException( "propertyName cannot be null or empty"); } } /** * Returns the value of the property named in the transformer's constructor for * the object provided. 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 ignoreNull * attribute. By default, <code>ignoreNull is 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 transformed. * @return The value of the property named in the transformer's constructor for the object * provided. * @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 is set to false. */ public Object transform(Object object) { Object propertyValue = null; try { propertyValue = PropertyUtils.getProperty(object, propertyName); } catch (IllegalArgumentException e) { final String errorMsg = "Problem during transformation. 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 = "No property found for name [" + propertyName + "]"; IllegalArgumentException iae = new IllegalArgumentException(errorMsg); if (!BeanUtils.initCause(iae, e)) { log.error(errorMsg, e); } throw iae; } return propertyValue; } /** * Returns the name of the property that will be used in the transformation of the bean. * * @return The name of the property that will be used in the transformation of the bean. */ public String getPropertyName() { return propertyName; } /** * Returns the flag which determines whether <code>null objects in the property path will * genenerate an <code>IllegalArgumentException or not. If set to true then * if any objects in the property path evaluate to <code>null then the * <code>IllegalArgumentException throw by PropertyUtils will be logged but * not rethrown and <code>null will be returned. If set to false then if any * objects in the property path evaluate to <code>null then the * <code>IllegalArgumentException throw by PropertyUtils will be logged and * rethrown. * * @return The flag which determines whether <code>null objects in the property path will * genenerate an <code>IllegalArgumentException or not. */ public boolean isIgnoreNull() { return ignoreNull; } }

Other Commons Beanutils examples (source code examples)

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