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 */
019package org.apache.commons.compress.archivers.jar;
020
021import java.io.IOException;
022import java.io.InputStream;
023
024import org.apache.commons.compress.archivers.ArchiveEntry;
025import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
026import 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 */
033public class JarArchiveInputStream extends ZipArchiveInputStream {
034
035    /**
036     * Creates an instance from the input stream using the default encoding.
037     *
038     * @param inputStream the input stream to wrap
039     */
040    public JarArchiveInputStream( final InputStream inputStream ) {
041        super(inputStream);
042    }
043
044    /**
045     * Creates an instance from the input stream using the specified encoding.
046     *
047     * @param inputStream the input stream to wrap
048     * @param encoding the encoding to use
049     * @since 1.10
050     */
051    public JarArchiveInputStream( final InputStream inputStream, final String encoding ) {
052        super(inputStream, encoding);
053    }
054
055    public JarArchiveEntry getNextJarEntry() throws IOException {
056        final ZipArchiveEntry entry = getNextZipEntry();
057        return entry == null ? null : new JarArchiveEntry(entry);
058    }
059
060    @Override
061    public ArchiveEntry getNextEntry() throws IOException {
062        return getNextJarEntry();
063    }
064
065    /**
066     * Checks if the signature matches what is expected for a jar file
067     * (in this case it is the same as for a zip file).
068     *
069     * @param signature
070     *            the bytes to check
071     * @param length
072     *            the number of bytes to check
073     * @return true, if this stream is a jar archive stream, false otherwise
074     */
075    public static boolean matches(final byte[] signature, final int length ) {
076        return ZipArchiveInputStream.matches(signature, length);
077    }
078}