    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.io.File;
    020import java.net.URL;
    021
    022import org.apache.commons.lang3.StringUtils;
    023
    024/**
    025 * <p>
    026 * A specialized implementation of {@code FileLocationStrategy} which tries to construct a file path from the locator's
    027 * base path and file name.
    028 * </p>
    029 * <p>
    030 * This strategies ignores the URL stored in the passed in {@link FileLocator}. It generates a path by concatenating the
    031 * base path (if present) and the file name. If the resulting path points to a valid file, the corresponding URL is
    032 * returned.
    033 * </p>
    034 *
    035 * @since 2.0
    036 */
    037public class BasePathLocationStrategy implements FileLocationStrategy {
    038
    039    /**
    040     * A singleton instance of this strategy.
    041     */
    042    static final BasePathLocationStrategy INSTANCE = new BasePathLocationStrategy();
    043
    044    /**
    045     * Constructs a new instance.
    046     */
    047    public BasePathLocationStrategy() {
    048        // empty
    049    }
    050
    051    /**
    052     * {@inheritDoc} This implementation uses utility methods from {@code FileLocatorUtils} to generate a {@code File} from
    053     * the locator's base path and file name. If this {@code File} exists, its URL is returned.
    054     */
    055    @Override
    056    public URL locate(final FileSystem fileSystem, final FileLocator locator) {
    057        if (StringUtils.isNotEmpty(locator.getFileName())) {
    058            final File file = FileLocatorUtils.constructFile(locator.getBasePath(), locator.getFileName());
    059            if (file.isFile()) {
    060                return FileLocatorUtils.convertFileToURL(file);
    061            }
    062        }
    063
    064        return null;
    065    }
    066}