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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.
*/
package java.util.zip;
import libcore.io.Streams;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
/**
* An {@code InputStream} filter to compress data. Callers read
* compressed data in the "deflate" format from the uncompressed
* underlying stream.
* @since 1.6
*/
public class DeflaterInputStream extends FilterInputStream {
private static final int DEFAULT_BUFFER_SIZE = 1024;
protected final Deflater def;
protected final byte[] buf;
private boolean closed = false;
private boolean available = true;
/**
* Constructs a {@code DeflaterInputStream} with a new {@code Deflater} and an
* implementation-defined default internal buffer size. {@code in} is a source of
* uncompressed data, and this stream will be a source of compressed data.
*
* @param in the source {@code InputStream}
*/
public DeflaterInputStream(InputStream in) {
this(in, new Deflater(), DEFAULT_BUFFER_SIZE);
}
/**
* Constructs a {@code DeflaterInputStream} with the given {@code Deflater} and an
* implementation-defined default internal buffer size. {@code in} is a source of
* uncompressed data, and this stream will be a source of compressed data.
*
* @param in the source {@code InputStream}
* @param deflater the {@code Deflater} to be used for compression
*/
public DeflaterInputStream(InputStream in, Deflater deflater) {
this(in, deflater, DEFAULT_BUFFER_SIZE);
}
/**
* Constructs a {@code DeflaterInputStream} with the given {@code Deflater} and
* given internal buffer size. {@code in} is a source of
* uncompressed data, and this stream will be a source of compressed data.
*
* @param in the source {@code InputStream}
* @param deflater the {@code Deflater} to be used for compression
* @param bufferSize the length in bytes of the internal buffer
*/
public DeflaterInputStream(InputStream in, Deflater deflater, int bufferSize) {
super(in);
if (in == null) {
throw new NullPointerException("in == null");
} else if (deflater == null) {
throw new NullPointerException("deflater == null");
}
if (bufferSize <= 0) {
throw new IllegalArgumentException("bufferSize <= 0: " + bufferSize);
}
this.def = deflater;
this.buf = new byte[bufferSize];
}
/**
* Closes the underlying input stream and discards any remaining uncompressed
* data.
*/
@Override
public void close() throws IOException {
closed = true;
def.end();
in.close();
}
/**
* Reads a byte from the compressed input stream. The result will be a byte of compressed
* data corresponding to an uncompressed byte or bytes read from the underlying stream.
*
* @return the byte or -1 if the end of the stream has been reached.
*/
@Override
public int read() throws IOException {
return Streams.readSingleByte(this);
}
/**
* Reads up to {@code byteCount} bytes of compressed data into a byte buffer. The result will be bytes of compressed
* data corresponding to an uncompressed byte or bytes read from the underlying stream.
* Returns the number of bytes read or -1 if the end of the compressed input
* stream has been reached.
*/
@Override
public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
checkClosed();
Arrays.checkOffsetAndCount(buffer.length, byteOffset, byteCount);
if (byteCount == 0) {
return 0;
}
if (!available) {
return -1;
}
int count = 0;
while (count < byteCount && !def.finished()) {
if (def.needsInput()) {
// read data from input stream
int bytesRead = in.read(buf);
if (bytesRead == -1) {
def.finish();
} else {
def.setInput(buf, 0, bytesRead);
}
}
int bytesDeflated = def.deflate(buf, 0, Math.min(buf.length, byteCount - count));
if (bytesDeflated == -1) {
break;
}
System.arraycopy(buf, 0, buffer, byteOffset + count, bytesDeflated);
count += bytesDeflated;
}
if (count == 0) {
count = -1;
available = false;
}
return count;
}
/**
* {@inheritDoc}
* Note: if {@code n > Integer.MAX_VALUE}, this stream will only attempt to
* skip {@code Integer.MAX_VALUE} bytes.
*/
@Override
public long skip(long byteCount) throws IOException {
byteCount = Math.min(Integer.MAX_VALUE, byteCount);
return Streams.skipByReading(this, byteCount);
}
/**
* Returns 0 when when this stream has exhausted its input; and 1 otherwise.
* A result of 1 does not guarantee that further bytes can be returned,
* with or without blocking.
*
*
Although consistent with the RI, this behavior is inconsistent with
* {@link InputStream#available()}, and violates the Liskov
* Substitution Principle. This method should not be used.
*
* @return 0 if no further bytes are available. Otherwise returns 1,
* which suggests (but does not guarantee) that additional bytes are
* available.
* @throws IOException if this stream is closed or an error occurs
*/
@Override
public int available() throws IOException {
checkClosed();
return available ? 1 : 0;
}
/**
* Returns false because {@code DeflaterInputStream} does not support
* {@code mark}/{@code reset}.
*/
@Override
public boolean markSupported() {
return false;
}
/**
* This operation is not supported and does nothing.
*/
@Override
public void mark(int limit) {
}
/**
* This operation is not supported and throws {@code IOException}.
*/
@Override
public void reset() throws IOException {
throw new IOException();
}
private void checkClosed() throws IOException {
if (closed) {
throw new IOException("Stream is closed");
}
}
}