001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.configuration2.builder;
018
019import org.apache.commons.configuration2.beanutils.BeanHelper;
020import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
021
022/**
023 * <p>
024 * A specialized implementation of {@code DefaultParametersHandler} that copies the properties of a
025 * {@link BuilderParameters} object (passed at construction time) onto the object to be initialized.
026 * </p>
027 * <p>
028 * Using this handler implementation makes specifying default values pretty straight-forward: Just create a
029 * corresponding parameters object, initialize it as desired, and pass it to this class. When invoked the handler uses
030 * functionality from <em>Commons BeanUtils</em> to copy all properties defined in the associated parameters object onto
031 * the target object. This is based on reflection. Properties not available for the target object are silently ignored.
032 * If an exception occurs during the copy operation, it is re-thrown as a runtime exception.
033 * </p>
034 * <p>
035 * Note that there is no default way to create a defensive copy of the passed in parameters object; therefore, the
036 * reference is stored. This makes it possible to change the parameters object later on, and the changes will be
037 * effective when initializing objects afterwards. Client code should not rely on this feature.
038 * </p>
039 *
040 * @since 2.0
041 */
042public class CopyObjectDefaultHandler implements DefaultParametersHandler<Object> {
043    /** The source object with the properties to be initialized. */
044    private final BuilderParameters source;
045
046    /**
047     * Creates a new instance of {@code CopyObjectDefaultHandler} and initializes it with the specified source object. The
048     * properties defined by the source object are copied onto the objects to be initialized.
049     *
050     * @param src the source object (must not be <b>null</b>)
051     * @throws IllegalArgumentException if the source object is <b>null</b>
052     */
053    public CopyObjectDefaultHandler(final BuilderParameters src) {
054        if (src == null) {
055            throw new IllegalArgumentException("Source object must not be null!");
056        }
057        source = src;
058    }
059
060    /**
061     * Gets the source object of this handler. This is the object whose properties are copied on the objects to be
062     * initialized.
063     *
064     * @return the source object of this {@code CopyObjectDefaultHandler}
065     */
066    public BuilderParameters getSource() {
067        return source;
068    }
069
070    /**
071     * {@inheritDoc} This implementation uses {@code PropertyUtils.copyProperties()} to copy all defined properties from the
072     * source object onto the passed in parameters object. Both the map with properties (obtained via the
073     * {@code getParameters()} method of the source parameters object) and other properties of the source object are copied.
074     *
075     * @throws ConfigurationRuntimeException if an exception occurs
076     * @see BuilderParameters#getParameters()
077     */
078    @Override
079    public void initializeDefaults(final Object parameters) {
080        try {
081            BeanHelper.copyProperties(parameters, getSource().getParameters());
082            BeanHelper.copyProperties(parameters, getSource());
083        } catch (final Exception e) {
084            // Handle all reflection-related exceptions the same way
085            throw new ConfigurationRuntimeException(e);
086        }
087    }
088}