001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.commons.compress.archivers.jar;
020    
021    import java.io.IOException;
022    import java.io.InputStream;
023    
024    import org.apache.commons.compress.archivers.ArchiveEntry;
025    import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
026    import org.apache.commons.compress.archivers.zip.ZipArchiveInputStream;
027    
028    /**
029     * Implements an input stream that can read entries from jar files.
030     * 
031     * @NotThreadSafe
032     */
033    public class JarArchiveInputStream extends ZipArchiveInputStream {
034    
035        public JarArchiveInputStream( final InputStream inputStream ) {
036            super(inputStream);
037        }
038    
039        public JarArchiveEntry getNextJarEntry() throws IOException {
040            ZipArchiveEntry entry = getNextZipEntry();
041            return entry == null ? null : new JarArchiveEntry(entry);
042        }
043    
044        @Override
045        public ArchiveEntry getNextEntry() throws IOException {
046            return getNextJarEntry();
047        }
048    
049        /**
050         * Checks if the signature matches what is expected for a jar file
051         * (in this case it is the same as for a zip file).
052         * 
053         * @param signature
054         *            the bytes to check
055         * @param length
056         *            the number of bytes to check
057         * @return true, if this stream is a jar archive stream, false otherwise
058         */
059        public static boolean matches(byte[] signature, int length ) {
060            return ZipArchiveInputStream.matches(signature, length);
061        }
062    }