Mega Code Archive
A collection of utility methods for working on GZIPed data
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/**
* 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.
*/
import java.io.ByteArrayOutputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
// Commons Logging imports
/**
* A collection of utility methods for working on GZIPed data.
*/
public class GZIPUtils {
private static final int EXPECTED_COMPRESSION_RATIO= 5;
private static final int BUF_SIZE= 4096;
/**
* Returns an gunzipped copy of the input array. If the gzipped
* input has been truncated or corrupted, a best-effort attempt is
* made to unzip as much as possible. If no data can be extracted
* <code>null</code> is returned.
*/
public static final byte[] unzipBestEffort(byte[] in) {
return unzipBestEffort(in, Integer.MAX_VALUE);
}
/**
* Returns an gunzipped copy of the input array, truncated to
* <code>sizeLimit</code> bytes, if necessary. If the gzipped input
* has been truncated or corrupted, a best-effort attempt is made to
* unzip as much as possible. If no data can be extracted
* <code>null</code> is returned.
*/
public static final byte[] unzipBestEffort(byte[] in, int sizeLimit) {
try {
// decompress using GZIPInputStream
ByteArrayOutputStream outStream =
new ByteArrayOutputStream(EXPECTED_COMPRESSION_RATIO * in.length);
GZIPInputStream inStream =
new GZIPInputStream ( new ByteArrayInputStream(in) );
byte[] buf = new byte[BUF_SIZE];
int written = 0;
while (true) {
try {
int size = inStream.read(buf);
if (size <= 0)
break;
if ((written + size) > sizeLimit) {
outStream.write(buf, 0, sizeLimit - written);
break;
}
outStream.write(buf, 0, size);
written+= size;
} catch (Exception e) {
break;
}
}
try {
outStream.close();
} catch (IOException e) {
}
return outStream.toByteArray();
} catch (IOException e) {
return null;
}
}
/**
* Returns an gunzipped copy of the input array.
* @throws IOException if the input cannot be properly decompressed
*/
public static final byte[] unzip(byte[] in) throws IOException {
// decompress using GZIPInputStream
ByteArrayOutputStream outStream =
new ByteArrayOutputStream(EXPECTED_COMPRESSION_RATIO * in.length);
GZIPInputStream inStream =
new GZIPInputStream ( new ByteArrayInputStream(in) );
byte[] buf = new byte[BUF_SIZE];
while (true) {
int size = inStream.read(buf);
if (size <= 0)
break;
outStream.write(buf, 0, size);
}
outStream.close();
return outStream.toByteArray();
}
/**
* Returns an gzipped copy of the input array.
*/
public static final byte[] zip(byte[] in) {
try {
// compress using GZIPOutputStream
ByteArrayOutputStream byteOut=
new ByteArrayOutputStream(in.length / EXPECTED_COMPRESSION_RATIO);
GZIPOutputStream outStream= new GZIPOutputStream(byteOut);
try {
outStream.write(in);
} catch (Exception e) {
}
try {
outStream.close();
} catch (IOException e) {
}
return byteOut.toByteArray();
} catch (IOException e) {
return null;
}
}
}
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