    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 *
    017 */
    018
    019package org.apache.commons.compress.utils;
    020
    021import java.io.File;
    022
    023/**
    024 * Generic file name utilities.
    025 * @since 1.20
    026 */
    027public class FileNameUtils {
    028
    029    /**
    030     * Returns the extension (i.e. the part after the last ".") of a file.
    031     *
    032     * <p>Will return an empty string if the file name doesn't contain
    033     * any dots. Only the last segment of a the file name is consulted
    034     * - i.e. all leading directories of the {@code filename}
    035     * parameter are skipped.</p>
    036     *
    037     * @return the extension of filename
    038     * @param filename the name of the file to obtain the extension of.
    039     */
    040    public static String getExtension(final String filename) {
    041        if (filename == null) {
    042            return null;
    043        }
    044
    045        final String name = new File(filename).getName();
    046        final int extensionPosition = name.lastIndexOf('.');
    047        if (extensionPosition < 0) {
    048            return "";
    049        }
    050        return name.substring(extensionPosition + 1);
    051    }
    052
    053    /**
    054     * Returns the basename (i.e. the part up to and not including the
    055     * last ".") of the last path segment of a filename.
    056     *
    057     * <p>Will return the file name itself if it doesn't contain any
    058     * dots. All leading directories of the {@code filename} parameter
    059     * are skipped.</p>
    060     *
    061     * @return the basename of filename
    062     * @param filename the name of the file to obtain the basename of.
    063     */
    064    public static String getBaseName(final String filename) {
    065        if (filename == null) {
    066            return null;
    067        }
    068
    069        final String name = new File(filename).getName();
    070
    071        final int extensionPosition = name.lastIndexOf('.');
    072        if (extensionPosition < 0) {
    073            return name;
    074        }
    075
    076        return name.substring(0, extensionPosition);
    077    }
    078}