/*
* Copyright 2005-2014 Red Hat, Inc.
* Red Hat 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.hornetq.utils;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.DataFormatException;
import java.util.zip.Inflater;
/**
* An InflaterReader
* It takes an compressed input stream and decompressed it as it is being read.
* Not for concurrent use.
*
* @author <a href="mailto:hgao@redhat.com">Howard Gao</a>
*/
public class InflaterReader extends InputStream
{
private Inflater inflater = new Inflater();
private InputStream input;
private byte[] readBuffer;
private int pointer;
private int length;
public InflaterReader(InputStream input)
{
this(input, 1024);
}
public InflaterReader(InputStream input, int bufferSize)
{
this.input = input;
this.readBuffer = new byte[bufferSize];
this.pointer = -1;
}
public int read() throws IOException
{
if (pointer == -1)
{
try
{
length = doRead(readBuffer, 0, readBuffer.length);
if (length == 0)
{
return -1;
}
pointer = 0;
}
catch (DataFormatException e)
{
IOException e2 = new IOException(e.getMessage());
e2.initCause(e);
throw e2;
}
}
int value = readBuffer[pointer] & 0xFF;
pointer++;
if (pointer == length)
{
pointer = -1;
}
return value;
}
/*
* feed inflater more bytes in order to get some
* decompressed output.
* returns number of bytes actually got
*/
private int doRead(byte[] buf, int offset, int len) throws DataFormatException, IOException
{
int read = 0;
int n = 0;
byte[] inputBuffer = new byte[len];
while (len > 0)
{
n = inflater.inflate(buf, offset, len);
if (n == 0)
{
if (inflater.finished())
{
break;
}
else if (inflater.needsInput())
{
//feeding
int m = input.read(inputBuffer);
if (m == -1)
{
//it shouldn't be here, throw exception
throw new DataFormatException("Input is over while inflater still expecting data");
}
else
{
//feed the data in
inflater.setInput(inputBuffer, 0, m);
n = inflater.inflate(buf, offset, len);
if (n > 0)
{
read += n;
offset += n;
len -= n;
}
}
}
else
{
//it shouldn't be here, throw
throw new DataFormatException("Inflater is neither finished nor needing input.");
}
}
else
{
read += n;
offset += n;
len -= n;
}
}
return read;
}
}