    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 *     https://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.Collection;
    020import java.util.Collections;
    021import java.util.Map;
    022import java.util.Set;
    023import java.util.stream.Collectors;
    024
    025import org.apache.commons.configuration2.FileBasedConfiguration;
    026import org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder;
    027import org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder;
    028import org.apache.commons.configuration2.ex.ConfigurationException;
    029import org.apache.commons.configuration2.reloading.CombinedReloadingController;
    030import org.apache.commons.configuration2.reloading.ReloadingController;
    031import org.apache.commons.configuration2.reloading.ReloadingControllerSupport;
    032
    033/**
    034 * <p>
    035 * A specialized {@code MultiFileConfigurationBuilder} implementation which adds support for reloading.
    036 * </p>
    037 * <p>
    038 * This class - as its super class - allows operating on multiple configuration files whose file names are determined
    039 * using a file name pattern and a {@code ConfigurationInterpolator} object. It provides the following additional
    040 * features:
    041 * </p>
    042 * <ul>
    043 * <li>Configuration builder for managed configurations have reloading support. So reloading is possible for all
    044 * configuration sources loaded by this builder instance.</li>
    045 * <li>A {@link ReloadingController} is provided which can be used to trigger reload checks on all managed
    046 * configurations.</li>
    047 * </ul>
    048 * <p>
    049 * Although this builder manages an arbitrary number of child configurations, to clients only a single configuration is
    050 * visible - the one selected by the evaluation of the file name pattern. Builder reset notifications triggered by the
    051 * reloading mechanism do not really take this fact into account; they are not limited to the currently selected child
    052 * configuration, but occur for each of the managed configuration.
    053 * </p>
    054 *
    055 * @param <T> the concrete type of {@code Configuration} objects created by this builder
    056 * @since 2.0
    057 */
    058public class ReloadingMultiFileConfigurationBuilder<T extends FileBasedConfiguration> extends MultiFileConfigurationBuilder<T>
    059    implements ReloadingControllerSupport {
    060    /** The reloading controller used by this builder. */
    061    private final ReloadingController reloadingController = createReloadingController();
    062
    063    /**
    064     * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} without setting initialization parameters.
    065     *
    066     * @param resCls the result configuration class
    067     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    068     */
    069    public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls) {
    070        super(resCls);
    071    }
    072
    073    /**
    074     * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} and sets initialization parameters.
    075     *
    076     * @param resCls the result configuration class
    077     * @param params a map with initialization parameters
    078     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    079     */
    080    public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls, final Map<String, Object> params) {
    081        super(resCls, params);
    082    }
    083
    084    /**
    085     * Creates a new instance of {@code ReloadingMultiFileConfigurationBuilder} and sets initialization parameters and a
    086     * flag whether initialization failures should be ignored.
    087     *
    088     * @param resCls the result configuration class
    089     * @param params a map with initialization parameters
    090     * @param allowFailOnInit a flag whether initialization errors should be ignored
    091     * @throws IllegalArgumentException if the result class is <strong>null</strong>
    092     */
    093    public ReloadingMultiFileConfigurationBuilder(final Class<T> resCls, final Map<String, Object> params, final boolean allowFailOnInit) {
    094        super(resCls, params, allowFailOnInit);
    095    }
    096
    097    /**
    098     * {@inheritDoc} This implementation returns a file-based configuration builder with reloading support.
    099     */
    100    @Override
    101    protected FileBasedConfigurationBuilder<T> createManagedBuilder(final String fileName, final Map<String, Object> params) throws ConfigurationException {
    102        return new ReloadingFileBasedConfigurationBuilder<>(getResultClass(), params, isAllowFailOnInit());
    103    }
    104
    105    /**
    106     * Creates the reloading controller used by this builder. This method creates a specialized
    107     * {@link CombinedReloadingController} which operates on the reloading controllers of the managed builders created so
    108     * far.
    109     *
    110     * @return the newly created {@code ReloadingController}
    111     */
    112    private ReloadingController createReloadingController() {
    113        final Set<ReloadingController> empty = Collections.emptySet();
    114        return new CombinedReloadingController(empty) {
    115            @Override
    116            public Collection<ReloadingController> getSubControllers() {
    117                return getManagedBuilders().values().stream().map(b -> ((ReloadingControllerSupport) b).getReloadingController()).collect(Collectors.toList());
    118            }
    119        };
    120    }
    121
    122    /**
    123     * {@inheritDoc} This implementation returns a special {@code ReloadingController} that delegates to the reloading
    124     * controllers of the managed builders created so far.
    125     */
    126    @Override
    127    public ReloadingController getReloadingController() {
    128        return reloadingController;
    129    }
    130}