    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.combined;
    018
    019import java.util.Arrays;
    020import java.util.Collection;
    021
    022import org.apache.commons.configuration2.CombinedConfiguration;
    023import org.apache.commons.configuration2.Configuration;
    024import org.apache.commons.configuration2.builder.BasicBuilderParameters;
    025import org.apache.commons.configuration2.builder.BasicConfigurationBuilder;
    026import org.apache.commons.configuration2.builder.BuilderParameters;
    027
    028/**
    029 * <p>
    030 * A specialized {@code ConfigurationBuilderProvider} implementation which deals with combined configuration builders.
    031 * </p>
    032 * <p>
    033 * This class is used to support {@code <configuration>} elements in configuration definition files. The provider
    034 * creates another {@link CombinedConfigurationBuilder} which inherits some of the properties from its parent builder.
    035 * </p>
    036 *
    037 * @since 2.0
    038 */
    039public class CombinedConfigurationBuilderProvider extends BaseConfigurationBuilderProvider {
    040    /** Constant for the name of the supported builder class. */
    041    private static final String BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.CombinedConfigurationBuilder";
    042
    043    /** Constant for the name of the supported reloading builder class. */
    044    private static final String RELOADING_BUILDER_CLASS = "org.apache.commons.configuration2.builder.combined.ReloadingCombinedConfigurationBuilder";
    045
    046    /** Constant for the name of the supported configuration class. */
    047    private static final String CONFIGURATION_CLASS = "org.apache.commons.configuration2.CombinedConfiguration";
    048
    049    /** Constant for the combined configuration builder parameters class. */
    050    private static final String COMBINED_PARAMS = "org.apache.commons.configuration2.builder.combined.CombinedBuilderParametersImpl";
    051
    052    /** Constant for the name of the file-based builder parameters class. */
    053    private static final String FILE_PARAMS = "org.apache.commons.configuration2.builder.FileBasedBuilderParametersImpl";
    054
    055    /**
    056     * Creates a new instance of {@code CombinedConfigurationBuilderProvider}.
    057     */
    058    public CombinedConfigurationBuilderProvider() {
    059        super(BUILDER_CLASS, RELOADING_BUILDER_CLASS, CONFIGURATION_CLASS, Arrays.asList(COMBINED_PARAMS, FILE_PARAMS));
    060    }
    061
    062    /**
    063     * {@inheritDoc} This implementation creates the result builder object directly, not using reflection. (The
    064     * reflection-based approach of the base class does not work here because a combined configuration builder has
    065     * constructors with a different signature.) It also performs some additional initializations.
    066     */
    067    @Override
    068    protected BasicConfigurationBuilder<? extends Configuration> createBuilder(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params)
    069        throws Exception {
    070        final CombinedConfigurationBuilder builder;
    071        if (decl.isReload()) {
    072            builder = new ReloadingCombinedConfigurationBuilder();
    073        } else {
    074            builder = new CombinedConfigurationBuilder();
    075        }
    076        decl.getConfigurationBuilder().initChildEventListeners(builder);
    077        return builder;
    078    }
    079
    080    /**
    081     * {@inheritDoc} This implementation pre-fills basic parameters from the basic properties of the parent builder's result
    082     * configuration.
    083     */
    084    @Override
    085    protected void initializeParameterObjects(final ConfigurationDeclaration decl, final Collection<BuilderParameters> params) throws Exception {
    086        // we know that the first object is the combined builder parameters
    087        // object
    088        final BasicBuilderParameters basicParams = (BasicBuilderParameters) params.iterator().next();
    089        setUpBasicParameters(decl.getConfigurationBuilder().getConfigurationUnderConstruction(), basicParams);
    090        // now properties set explicitly can be overridden
    091        super.initializeParameterObjects(decl, params);
    092    }
    093
    094    /**
    095     * Populates the specified parameters object with properties from the given configuration. This method is used to set
    096     * default values for basic properties based on the result configuration of the parent builder.
    097     *
    098     * @param config the configuration whose properties are to be copied
    099     * @param params the target parameters object
    100     */
    101    private static void setUpBasicParameters(final CombinedConfiguration config, final BasicBuilderParameters params) {
    102        params.setListDelimiterHandler(config.getListDelimiterHandler()).setLogger(config.getLogger())
    103            .setThrowExceptionOnMissing(config.isThrowExceptionOnMissing()).setConfigurationDecoder(config.getConfigurationDecoder());
    104    }
    105}