XZ for Java 1.9 · org.tukaani.xz.LZMA2InputStream

Field Summary

Modifier and Type	Field and Description
private final ArrayCache	arrayCache
private static final int	COMPRESSED_SIZE_MAX
public static final int	DICT_SIZE_MAX Largest dictionary size supported by this implementation.
public static final int	DICT_SIZE_MIN Smallest valid LZMA2 dictionary size.
private boolean	endReached
private IOException	exception
private DataInputStream	in
private boolean	isLZMAChunk
private LZDecoder	lz
private LZMADecoder	lzma
private boolean	needDictReset
private boolean	needProps
private RangeDecoderFromBuffer	rc
private final byte[]	tempBuf
private int	uncompressedSize

Constructor Summary

Access	Constructor and Description
public	LZMA2InputStream(InputStream input stream from which LZMA2-compressed data is read in, int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] dictSize) Creates a new input stream that decompresses raw LZMA2 data from `in`.
public	LZMA2InputStream(InputStream input stream from which LZMA2-compressed data is read in, int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] dictSize, byte[] preset dictionary or `null` to use no preset dictionary presetDict) Creates a new LZMA2 decompressor using a preset dictionary.
pack-priv	LZMA2InputStream(InputStream input stream from which LZMA2-compressed data is read in, int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] dictSize, byte[] preset dictionary or `null` to use no preset dictionary presetDict, ArrayCache cache to be used for allocating large arrays arrayCache) Creates a new LZMA2 decompressor using a preset dictionary and array cache.

Method Summary

Modifier and Type	Method and Description
public int	Returns: the number of uncompressed bytes that can be read without blocking available() Overrides java.io.InputStream.available. Returns the number of uncompressed bytes that can be read without blocking.
public void	close() Overrides java.io.InputStream.close. Implements java.io.Closeable.close. Closes the stream and calls `in.close()`.
private void	decodeChunkHeader()
private void	decodeProps()
private static int	getDictSize(int dictSize)
public static int	Returns: approximate memory requirements as kibibytes (KiB) getMemoryUsage(int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] dictSize) Gets approximate decompressor memory requirements as kibibytes for the given dictionary size.
private void	putArraysToCache()
public int	Returns: the next decompressed byte, or `-1` to indicate the end of the compressed stream read() Implements abstract java.io.InputStream.read. Decompresses the next byte from this input stream.
public int	Returns: number of bytes read, or `-1` to indicate the end of the compressed stream read(byte[] target buffer for uncompressed data buf, int start offset in `buf` off, int maximum number of uncompressed bytes to read len) Overrides java.io.InputStream.read. Decompresses into an array of bytes.

Inherited from java.io.InputStream:: mark markSupported nullInputStream read readAllBytes readNBytes readNBytes reset skip skipNBytes transferTo

Field Detail

arrayCache	back to summary
private final ArrayCache arrayCache

COMPRESSED_SIZE_MAX	back to summary
private static final int COMPRESSED_SIZE_MAX

DICT_SIZE_MAX	back to summary
public static final int DICT_SIZE_MAX Largest dictionary size supported by this implementation. The LZMA2 algorithm allows dictionaries up to one byte less than 4 GiB. This implementation supports only 16 bytes less than 2 GiB for raw LZMA2 streams, and for .xz files the maximum is 1.5 GiB. This limitation is due to Java using signed 32-bit integers for array indexing. The limitation shouldn't matter much in practice since so huge dictionaries are not normally used.

DICT_SIZE_MAX

back to summary

public static final int DICT_SIZE_MAX

Largest dictionary size supported by this implementation.

The LZMA2 algorithm allows dictionaries up to one byte less than 4 GiB. This implementation supports only 16 bytes less than 2 GiB for raw LZMA2 streams, and for .xz files the maximum is 1.5 GiB. This limitation is due to Java using signed 32-bit integers for array indexing. The limitation shouldn't matter much in practice since so huge dictionaries are not normally used.

DICT_SIZE_MIN	back to summary
public static final int DICT_SIZE_MIN Smallest valid LZMA2 dictionary size. Very tiny dictionaries would be a performance problem, so the minimum is 4 KiB.

DICT_SIZE_MIN

back to summary

public static final int DICT_SIZE_MIN

Smallest valid LZMA2 dictionary size.

Very tiny dictionaries would be a performance problem, so the minimum is 4 KiB.

endReached	back to summary
private boolean endReached

exception	back to summary
private IOException exception

in	back to summary
private DataInputStream in

isLZMAChunk	back to summary
private boolean isLZMAChunk

lz	back to summary
private LZDecoder lz

lzma	back to summary
private LZMADecoder lzma

needDictReset	back to summary
private boolean needDictReset

needProps	back to summary
private boolean needProps

rc	back to summary
private RangeDecoderFromBuffer rc

tempBuf	back to summary
private final byte[] tempBuf

uncompressedSize	back to summary
private int uncompressedSize

Constructor Detail

LZMA2InputStream back to summary

LZMA2InputStream	back to summary
public LZMA2InputStream(InputStream in, int dictSize) Creates a new input stream that decompresses raw LZMA2 data from `in`. The caller needs to know the dictionary size used when compressing; the dictionary size isn't stored as part of a raw LZMA2 stream. Specifying a too small dictionary size will prevent decompressing the stream. Specifying a too big dictionary is waste of memory but decompression will work. There is no need to specify a dictionary bigger than the uncompressed size of the data even if a bigger dictionary was used when compressing. If you know the uncompressed size of the data, this might allow saving some memory. Parameters in:InputStream input stream from which LZMA2-compressed data is read dictSize:int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`]

public LZMA2InputStream(InputStream in, int dictSize)

Creates a new input stream that decompresses raw LZMA2 data from in.

The caller needs to know the dictionary size used when compressing; the dictionary size isn't stored as part of a raw LZMA2 stream.

Specifying a too small dictionary size will prevent decompressing the stream. Specifying a too big dictionary is waste of memory but decompression will work.

There is no need to specify a dictionary bigger than the uncompressed size of the data even if a bigger dictionary was used when compressing. If you know the uncompressed size of the data, this might allow saving some memory.

Parameters

in:InputStream: input stream from which LZMA2-compressed data is read
dictSize:int: LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN, DICT_SIZE_MAX]

LZMA2InputStream back to summary

LZMA2InputStream	back to summary
public LZMA2InputStream(InputStream in, int dictSize, byte[] presetDict) Creates a new LZMA2 decompressor using a preset dictionary. This is like `LZMA2InputStream(InputStream, int)` except that the dictionary may be initialized using a preset dictionary. If a preset dictionary was used when compressing the data, the same preset dictionary must be provided when decompressing. Parameters in:InputStream input stream from which LZMA2-compressed data is read dictSize:int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] presetDict:byte[] preset dictionary or `null` to use no preset dictionary

public LZMA2InputStream(InputStream in, int dictSize, byte[] presetDict)

Creates a new LZMA2 decompressor using a preset dictionary.

This is like LZMA2InputStream(InputStream, int) except that the dictionary may be initialized using a preset dictionary. If a preset dictionary was used when compressing the data, the same preset dictionary must be provided when decompressing.

Parameters

in:InputStream: input stream from which LZMA2-compressed data is read
dictSize:int: LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN, DICT_SIZE_MAX]
presetDict:byte[]: preset dictionary or null to use no preset dictionary

LZMA2InputStream back to summary

LZMA2InputStream	back to summary
pack-priv LZMA2InputStream(InputStream in, int dictSize, byte[] presetDict, ArrayCache arrayCache) Creates a new LZMA2 decompressor using a preset dictionary and array cache. This is like `LZMA2InputStream(InputStream, int, byte[])` except that this also takes the `arrayCache` argument. Parameters in:InputStream input stream from which LZMA2-compressed data is read dictSize:int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] presetDict:byte[] preset dictionary or `null` to use no preset dictionary arrayCache:ArrayCache cache to be used for allocating large arrays Since 1.7

pack-priv LZMA2InputStream(InputStream in, int dictSize, byte[] presetDict, ArrayCache arrayCache)

Creates a new LZMA2 decompressor using a preset dictionary and array cache.

This is like LZMA2InputStream(InputStream, int, byte[]) except that this also takes the arrayCache argument.

Parameters

in:InputStream: input stream from which LZMA2-compressed data is read
dictSize:int: LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN, DICT_SIZE_MAX]
presetDict:byte[]: preset dictionary or null to use no preset dictionary
arrayCache:ArrayCache: cache to be used for allocating large arrays

Since

1.7

Method Detail

available back to summary

available	back to summary
public int available() throws IOException Overrides java.io.InputStream.available. Returns the number of uncompressed bytes that can be read without blocking. The value is returned with an assumption that the compressed input data will be valid. If the compressed data is corrupt, `CorruptedInputException` may get thrown before the number of bytes claimed to be available have been read from this input stream. In LZMA2InputStream, the return value will be non-zero when the decompressor is in the middle of an LZMA2 chunk. The return value will then be the number of uncompressed bytes remaining from that chunk. The return value can also be non-zero in the middle of an uncompressed chunk, but then the return value depends also on the `available()` method of the underlying InputStream. Returns:int the number of uncompressed bytes that can be read without blocking Exceptions IOException: Doc from java.io.InputStream.available. if an I/O error occurs.

public int available() throws IOException

Overrides java.io.InputStream.available.

Returns the number of uncompressed bytes that can be read without blocking. The value is returned with an assumption that the compressed input data will be valid. If the compressed data is corrupt, CorruptedInputException may get thrown before the number of bytes claimed to be available have been read from this input stream.

In LZMA2InputStream, the return value will be non-zero when the decompressor is in the middle of an LZMA2 chunk. The return value will then be the number of uncompressed bytes remaining from that chunk. The return value can also be non-zero in the middle of an uncompressed chunk, but then the return value depends also on the available() method of the underlying InputStream.

Returns:int

the number of uncompressed bytes that can be read without blocking

Exceptions

IOException:

Doc from java.io.InputStream.available.

if an I/O error occurs.

close back to summary

close	back to summary
public void close() throws IOException Overrides java.io.InputStream.close. Implements java.io.Closeable.close. Closes the stream and calls `in.close()`. If the stream was already closed, this does nothing. Exceptions IOException: if thrown by `in.close()`

public void close() throws IOException

Overrides java.io.InputStream.close.

Implements java.io.Closeable.close.

Closes the stream and calls in.close(). If the stream was already closed, this does nothing.

Exceptions

IOException:: if thrown by in.close()

decodeChunkHeader	back to summary
private void decodeChunkHeader() throws IOException

decodeProps	back to summary
private void decodeProps() throws IOException

getDictSize	back to summary
private static int getDictSize(int dictSize)

getMemoryUsage back to summary

getMemoryUsage	back to summary
public static int getMemoryUsage(int dictSize) Gets approximate decompressor memory requirements as kibibytes for the given dictionary size. Parameters dictSize:int LZMA2 dictionary size as bytes, must be in the range [`DICT_SIZE_MIN`, `DICT_SIZE_MAX`] Returns:int approximate memory requirements as kibibytes (KiB)

public static int getMemoryUsage(int dictSize)

Gets approximate decompressor memory requirements as kibibytes for the given dictionary size.

Parameters

dictSize:int: LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN, DICT_SIZE_MAX]

Returns:int

approximate memory requirements as kibibytes (KiB)

putArraysToCache	back to summary
private void putArraysToCache()

read back to summary

read	back to summary
public int read() throws IOException Implements abstract java.io.InputStream.read. Decompresses the next byte from this input stream. Reading lots of data with `read()` from this input stream may be inefficient. Wrap it in `java.io.BufferedInputStream` if you need to read lots of data one byte at a time. Returns:int the next decompressed byte, or `-1` to indicate the end of the compressed stream Exceptions IOException: may be thrown by `in` XZIOException: if the stream has been closed EOFException: compressed input is truncated or corrupt

public int read() throws IOException

Implements abstract java.io.InputStream.read.

Decompresses the next byte from this input stream.

Reading lots of data with read() from this input stream may be inefficient. Wrap it in java.io.BufferedInputStream if you need to read lots of data one byte at a time.

Returns:int

the next decompressed byte, or -1 to indicate the end of the compressed stream

Exceptions

IOException:: may be thrown by in
XZIOException:: if the stream has been closed
EOFException:: compressed input is truncated or corrupt

read back to summary

read	back to summary
public int read(byte[] buf, int off, int len) throws IOException Overrides java.io.InputStream.read. Decompresses into an array of bytes. If `len` is zero, no bytes are read and `0` is returned. Otherwise this will block until `len` bytes have been decompressed, the end of the LZMA2 stream is reached, or an exception is thrown. Parameters buf:byte[] target buffer for uncompressed data off:int start offset in `buf` len:int maximum number of uncompressed bytes to read Returns:int number of bytes read, or `-1` to indicate the end of the compressed stream Exceptions IOException: may be thrown by `in` XZIOException: if the stream has been closed EOFException: compressed input is truncated or corrupt

public int read(byte[] buf, int off, int len) throws IOException

Overrides java.io.InputStream.read.

Decompresses into an array of bytes.

If len is zero, no bytes are read and 0 is returned. Otherwise this will block until len bytes have been decompressed, the end of the LZMA2 stream is reached, or an exception is thrown.

Parameters

buf:byte[]: target buffer for uncompressed data
off:int: start offset in buf
len:int: maximum number of uncompressed bytes to read

Returns:int

number of bytes read, or -1 to indicate the end of the compressed stream

Exceptions

IOException:: may be thrown by in
XZIOException:: if the stream has been closed
EOFException:: compressed input is truncated or corrupt

public Class LZMA2InputStream

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail