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.io;
018
019import java.net.URL;
020
021import org.apache.commons.lang3.StringUtils;
022
023/**
024 * A specialized {@code FileLocationStrategy} implementation which searches for files on the class path.
025 * <p>
026 * This strategy implementation ignores the URL and the base path components of the passed in {@link FileLocator}. It
027 * tries to look up the file name on both the class path and the system class path.
028 * </p>
029 * <p>
030 * See {@link AbstractFileLocationStrategy} learn how to grant an deny URL schemes and hosts.
031 * </p>
032 *
033 * @see AbstractFileLocationStrategy
034 * @since 2.0
035 */
036public class ClasspathLocationStrategy extends AbstractFileLocationStrategy {
037
038    /**
039     * Builds new instances of {@link ProvidedURLLocationStrategy}.
040     *
041     * @return a new builder.
042     * @since 2.15.0
043     */
044    public static StrategyBuilder<ClasspathLocationStrategy> builder() {
045        return new StrategyBuilder<>(ClasspathLocationStrategy::new);
046    }
047
048    /**
049     * Constructs a new instance.
050     */
051    public ClasspathLocationStrategy() {
052        // empty
053    }
054
055    /**
056     * Constructs a new instance.
057     *
058     * @param builder How to build the instance.
059     * @since 2.15.0
060     */
061    public ClasspathLocationStrategy(final AbstractBuilder<?, ?> builder) {
062        super(builder);
063    }
064
065    /**
066     * {@inheritDoc} This implementation looks up the locator's file name as a resource on the class path.
067     */
068    @Override
069    public URL locate(final FileSystem fileSystem, final FileLocator locator) {
070        return check(StringUtils.isEmpty(locator.getFileName()) ? null : FileLocatorUtils.getClasspathResource(locator.getFileName()));
071    }
072}