org.apache.commons.compress.compressors.deflate.DeflateCompressorInputStream Maven / Gradle / Ivy
/*
* 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
*
* http://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.compress.compressors.deflate;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
import org.apache.commons.compress.compressors.CompressorInputStream;
/**
* Deflate decompressor.
* @since 1.9
*/
public class DeflateCompressorInputStream extends CompressorInputStream {
private static final int MAGIC_1 = 0x78;
private static final int MAGIC_2a = 0x01;
private static final int MAGIC_2b = 0x5e;
private static final int MAGIC_2c = 0x9c;
private static final int MAGIC_2d = 0xda;
private final InputStream in;
private final Inflater inflater;
/**
* Creates a new input stream that decompresses Deflate-compressed data
* from the specified input stream.
*
* @param inputStream where to read the compressed data
*
*/
public DeflateCompressorInputStream(final InputStream inputStream) {
this(inputStream, new DeflateParameters());
}
/**
* Creates a new input stream that decompresses Deflate-compressed data
* from the specified input stream.
*
* @param inputStream where to read the compressed data
* @param parameters parameters
*/
public DeflateCompressorInputStream(final InputStream inputStream,
final DeflateParameters parameters) {
inflater = new Inflater(!parameters.withZlibHeader());
in = new InflaterInputStream(inputStream, inflater);
}
/** {@inheritDoc} */
@Override
public int read() throws IOException {
final int ret = in.read();
count(ret == -1 ? 0 : 1);
return ret;
}
/** {@inheritDoc} */
@Override
public int read(final byte[] buf, final int off, final int len) throws IOException {
final int ret = in.read(buf, off, len);
count(ret);
return ret;
}
/** {@inheritDoc} */
@Override
public long skip(final long n) throws IOException {
return in.skip(n);
}
/** {@inheritDoc} */
@Override
public int available() throws IOException {
return in.available();
}
/** {@inheritDoc} */
@Override
public void close() throws IOException {
try {
in.close();
} finally {
inflater.end();
}
}
/**
* Checks if the signature matches what is expected for a zlib / deflated file
* with the zlib header.
*
* @param signature
* the bytes to check
* @param length
* the number of bytes to check
* @return true, if this stream is zlib / deflate compressed with a header
* stream, false otherwise
*
* @since 1.10
*/
public static boolean matches(final byte[] signature, final int length) {
return length > 3 && signature[0] == MAGIC_1 && (
signature[1] == (byte) MAGIC_2a ||
signature[1] == (byte) MAGIC_2b ||
signature[1] == (byte) MAGIC_2c ||
signature[1] == (byte) MAGIC_2d);
}
}