/*
* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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*/
package java.util.zip;
/**
* This class provides support for general purpose decompression using the
* popular ZLIB compression library. The ZLIB compression library was
* initially developed as part of the PNG graphics standard and is not
* protected by patents. It is fully described in the specifications at
* the <a href="package-summary.html#package_description">java.util.zip
* package description</a>.
*
* <p>The following code fragment demonstrates a trivial compression
* and decompression of a string using <tt>Deflater</tt> and
* <tt>Inflater</tt>.
*
* <blockquote><pre>
* try {
* // Encode a String into bytes
* String inputString = "blahblahblah\u20AC\u20AC";
* byte[] input = inputString.getBytes("UTF-8");
*
* // Compress the bytes
* byte[] output = new byte[100];
* Deflater compresser = new Deflater();
* compresser.setInput(input);
* compresser.finish();
* int compressedDataLength = compresser.deflate(output);
*
* // Decompress the bytes
* Inflater decompresser = new Inflater();
* decompresser.setInput(output, 0, compressedDataLength);
* byte[] result = new byte[100];
* int resultLength = decompresser.inflate(result);
* decompresser.end();
*
* // Decode the bytes into a String
* String outputString = new String(result, 0, resultLength, "UTF-8");
* } catch(java.io.UnsupportedEncodingException ex) {
* // handle
* } catch (java.util.zip.DataFormatException ex) {
* // handle
* }
* </pre></blockquote>
*
* @see Deflater
* @author David Connelly
*
*/
public
class
Inflater {
private final
ZStreamRef zsRef;
private byte[]
buf =
defaultBuf;
private int
off,
len;
private boolean
finished;
private boolean
needDict;
private long
bytesRead;
private long
bytesWritten;
private static final byte[]
defaultBuf = new byte[0];
static {
/* Zip library is loaded from System.initializeSystemClass */
initIDs();
}
/**
* Creates a new decompressor. If the parameter 'nowrap' is true then
* the ZLIB header and checksum fields will not be used. This provides
* compatibility with the compression format used by both GZIP and PKZIP.
* <p>
* Note: When using the 'nowrap' option it is also necessary to provide
* an extra "dummy" byte as input. This is required by the ZLIB native
* library in order to support certain optimizations.
*
* @param nowrap if true then support GZIP compatible compression
*/
public
Inflater(boolean
nowrap) {
zsRef = new
ZStreamRef(
init(
nowrap));
}
/**
* Creates a new decompressor.
*/
public
Inflater() {
this(false);
}
/**
* Sets input data for decompression. Should be called whenever
* needsInput() returns true indicating that more input data is
* required.
* @param b the input data bytes
* @param off the start offset of the input data
* @param len the length of the input data
* @see Inflater#needsInput
*/
public void
setInput(byte[]
b, int
off, int
len) {
if (
b == null) {
throw new
NullPointerException();
}
if (
off < 0 ||
len < 0 ||
off >
b.length -
len) {
throw new
ArrayIndexOutOfBoundsException();
}
synchronized (
zsRef) {
this.
buf =
b;
this.
off =
off;
this.
len =
len;
}
}
/**
* Sets input data for decompression. Should be called whenever
* needsInput() returns true indicating that more input data is
* required.
* @param b the input data bytes
* @see Inflater#needsInput
*/
public void
setInput(byte[]
b) {
setInput(
b, 0,
b.length);
}
/**
* Sets the preset dictionary to the given array of bytes. Should be
* called when inflate() returns 0 and needsDictionary() returns true
* indicating that a preset dictionary is required. The method getAdler()
* can be used to get the Adler-32 value of the dictionary needed.
* @param b the dictionary data bytes
* @param off the start offset of the data
* @param len the length of the data
* @see Inflater#needsDictionary
* @see Inflater#getAdler
*/
public void
setDictionary(byte[]
b, int
off, int
len) {
if (
b == null) {
throw new
NullPointerException();
}
if (
off < 0 ||
len < 0 ||
off >
b.length -
len) {
throw new
ArrayIndexOutOfBoundsException();
}
synchronized (
zsRef) {
ensureOpen();
setDictionary(
zsRef.
address(),
b,
off,
len);
needDict = false;
}
}
/**
* Sets the preset dictionary to the given array of bytes. Should be
* called when inflate() returns 0 and needsDictionary() returns true
* indicating that a preset dictionary is required. The method getAdler()
* can be used to get the Adler-32 value of the dictionary needed.
* @param b the dictionary data bytes
* @see Inflater#needsDictionary
* @see Inflater#getAdler
*/
public void
setDictionary(byte[]
b) {
setDictionary(
b, 0,
b.length);
}
/**
* Returns the total number of bytes remaining in the input buffer.
* This can be used to find out what bytes still remain in the input
* buffer after decompression has finished.
* @return the total number of bytes remaining in the input buffer
*/
public int
getRemaining() {
synchronized (
zsRef) {
return
len;
}
}
/**
* Returns true if no data remains in the input buffer. This can
* be used to determine if #setInput should be called in order
* to provide more input.
* @return true if no data remains in the input buffer
*/
public boolean
needsInput() {
synchronized (
zsRef) {
return
len <= 0;
}
}
/**
* Returns true if a preset dictionary is needed for decompression.
* @return true if a preset dictionary is needed for decompression
* @see Inflater#setDictionary
*/
public boolean
needsDictionary() {
synchronized (
zsRef) {
return
needDict;
}
}
/**
* Returns true if the end of the compressed data stream has been
* reached.
* @return true if the end of the compressed data stream has been
* reached
*/
public boolean
finished() {
synchronized (
zsRef) {
return
finished;
}
}
/**
* Uncompresses bytes into specified buffer. Returns actual number
* of bytes uncompressed. A return value of 0 indicates that
* needsInput() or needsDictionary() should be called in order to
* determine if more input data or a preset dictionary is required.
* In the latter case, getAdler() can be used to get the Adler-32
* value of the dictionary required.
* @param b the buffer for the uncompressed data
* @param off the start offset of the data
* @param len the maximum number of uncompressed bytes
* @return the actual number of uncompressed bytes
* @exception DataFormatException if the compressed data format is invalid
* @see Inflater#needsInput
* @see Inflater#needsDictionary
*/
public int
inflate(byte[]
b, int
off, int
len)
throws
DataFormatException
{
if (
b == null) {
throw new
NullPointerException();
}
if (
off < 0 ||
len < 0 ||
off >
b.length -
len) {
throw new
ArrayIndexOutOfBoundsException();
}
synchronized (
zsRef) {
ensureOpen();
int
thisLen = this.
len;
int
n =
inflateBytes(
zsRef.
address(),
b,
off,
len);
bytesWritten +=
n;
bytesRead += (
thisLen - this.
len);
return
n;
}
}
/**
* Uncompresses bytes into specified buffer. Returns actual number
* of bytes uncompressed. A return value of 0 indicates that
* needsInput() or needsDictionary() should be called in order to
* determine if more input data or a preset dictionary is required.
* In the latter case, getAdler() can be used to get the Adler-32
* value of the dictionary required.
* @param b the buffer for the uncompressed data
* @return the actual number of uncompressed bytes
* @exception DataFormatException if the compressed data format is invalid
* @see Inflater#needsInput
* @see Inflater#needsDictionary
*/
public int
inflate(byte[]
b) throws
DataFormatException {
return
inflate(
b, 0,
b.length);
}
/**
* Returns the ADLER-32 value of the uncompressed data.
* @return the ADLER-32 value of the uncompressed data
*/
public int
getAdler() {
synchronized (
zsRef) {
ensureOpen();
return
getAdler(
zsRef.
address());
}
}
/**
* Returns the total number of compressed bytes input so far.
*
* <p>Since the number of bytes may be greater than
* Integer.MAX_VALUE, the {@link #getBytesRead()} method is now
* the preferred means of obtaining this information.</p>
*
* @return the total number of compressed bytes input so far
*/
public int
getTotalIn() {
return (int)
getBytesRead();
}
/**
* Returns the total number of compressed bytes input so far.
*
* @return the total (non-negative) number of compressed bytes input so far
* @since 1.5
*/
public long
getBytesRead() {
synchronized (
zsRef) {
ensureOpen();
return
bytesRead;
}
}
/**
* Returns the total number of uncompressed bytes output so far.
*
* <p>Since the number of bytes may be greater than
* Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now
* the preferred means of obtaining this information.</p>
*
* @return the total number of uncompressed bytes output so far
*/
public int
getTotalOut() {
return (int)
getBytesWritten();
}
/**
* Returns the total number of uncompressed bytes output so far.
*
* @return the total (non-negative) number of uncompressed bytes output so far
* @since 1.5
*/
public long
getBytesWritten() {
synchronized (
zsRef) {
ensureOpen();
return
bytesWritten;
}
}
/**
* Resets inflater so that a new set of input data can be processed.
*/
public void
reset() {
synchronized (
zsRef) {
ensureOpen();
reset(
zsRef.
address());
buf =
defaultBuf;
finished = false;
needDict = false;
off =
len = 0;
bytesRead =
bytesWritten = 0;
}
}
/**
* Closes the decompressor and discards any unprocessed input.
* This method should be called when the decompressor is no longer
* being used, but will also be called automatically by the finalize()
* method. Once this method is called, the behavior of the Inflater
* object is undefined.
*/
public void
end() {
synchronized (
zsRef) {
long
addr =
zsRef.
address();
zsRef.
clear();
if (
addr != 0) {
end(
addr);
buf = null;
}
}
}
/**
* Closes the decompressor when garbage is collected.
*/
protected void
finalize() {
end();
}
private void
ensureOpen () {
assert
Thread.
holdsLock(
zsRef);
if (
zsRef.
address() == 0)
throw new
NullPointerException("Inflater has been closed");
}
boolean
ended() {
synchronized (
zsRef) {
return
zsRef.
address() == 0;
}
}
private native static void
initIDs();
private native static long
init(boolean
nowrap);
private native static void
setDictionary(long
addr, byte[]
b, int
off,
int
len);
private native int
inflateBytes(long
addr, byte[]
b, int
off, int
len)
throws
DataFormatException;
private native static int
getAdler(long
addr);
private native static void
reset(long
addr);
private native static void
end(long
addr);
}