src/main/java/org/apache/commons/configuration2/io/AbsoluteNameLocationStrategy.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.configuration2.io;

import java.io.File;
import java.net.URL;

import org.apache.commons.lang3.StringUtils;

/**
 * <p>
 * A specialized implementation of {@code FileLocationStrategy} which checks whether the provided file name is already
 * an absolute file name.
 * </p>
 * <p>
 * This strategy ignores the URL and the base path stored in the passed in {@link FileLocator}. It is only triggered by
 * absolute names in the locator's {@code fileName} component.
 * </p>
 *
 * @since 2.0
 */
public class AbsoluteNameLocationStrategy implements FileLocationStrategy {

    /**
     * A singleton instance of this strategy.
     */
    static final AbsoluteNameLocationStrategy INSTANCE = new AbsoluteNameLocationStrategy();

    /**
     * Constructs a new instance.
     */
    public AbsoluteNameLocationStrategy() {
        // empty
    }

    /**
     * {@inheritDoc} This implementation constructs a {@code File} object from the locator's file name (if defined). If this
     * results in an absolute file name pointing to an existing file, the corresponding URL is returned.
     */
    @Override
    public URL locate(final FileSystem fileSystem, final FileLocator locator) {
        if (StringUtils.isNotEmpty(locator.getFileName())) {
            final File file = new File(locator.getFileName());
            if (file.isAbsolute() && file.exists()) {
                return FileLocatorUtils.convertFileToURL(file);
            }
        }

        return null;
    }
}