001    /**
002     *
003     * Copyright 2005 The Apache Software Foundation
004     *
005     *  Licensed under the Apache License, Version 2.0 (the "License");
006     *  you may not use this file except in compliance with the License.
007     *  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    package org.apache.geronimo.common;
018    
019    import java.io.File;
020    import java.io.DataInputStream;
021    import java.io.BufferedInputStream;
022    import java.io.FileInputStream;
023    import java.io.IOException;
024    import java.util.zip.ZipFile;
025    
026    /**
027     * Utility functions related to Files.
028     *
029     * @version $Rev: 437254 $ $Date: 2006-08-26 17:07:55 -0700 (Sat, 26 Aug 2006) $
030     */
031    public class FileUtils {
032        /**
033         * Determine whether a file is a JAR File.
034         */
035        public static boolean isJarFile(File file) throws IOException {
036            if(!isZipFile(file)) {
037                return false;
038            }
039            ZipFile zip = new ZipFile(file);
040            boolean manifest = zip.getEntry("META-INF/MANIFEST.MF") != null;
041            zip.close();
042            return manifest;
043        }
044    
045        /**
046         * Determine whether a file is a ZIP File.
047         */
048        public static boolean isZipFile(File file) throws IOException {
049            if(file.isDirectory()) {
050                return false;
051            }
052            if(!file.canRead()) {
053                throw new IOException("Cannot read file "+file.getAbsolutePath());
054            }
055            if(file.length() < 4) {
056                return false;
057            }
058            DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
059            int test = in.readInt();
060            in.close();
061            return test == 0x504b0304;
062        }
063    
064    }