Class LZMA2InputStream
- All Implemented Interfaces:
Closeable
,AutoCloseable
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final int
Largest dictionary size supported by this implementation.static final int
Smallest valid LZMA2 dictionary size. -
Constructor Summary
ConstructorsConstructorDescriptionLZMA2InputStream
(InputStream in, int dictSize) Creates a new input stream that decompresses raw LZMA2 data fromin
.LZMA2InputStream
(InputStream in, int dictSize, byte[] presetDict) Creates a new LZMA2 decompressor using a preset dictionary. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns the number of uncompressed bytes that can be read without blocking.void
close()
Closes the stream and callsin.close()
.static int
getMemoryUsage
(int dictSize) Gets approximate decompressor memory requirements as kibibytes for the given dictionary size.int
read()
Decompresses the next byte from this input stream.int
read
(byte[] buf, int off, int len) Decompresses into an array of bytes.Methods inherited from class java.io.InputStream
mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skip, skipNBytes, transferTo
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Field Details
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DICT_SIZE_MIN
public static final int DICT_SIZE_MINSmallest valid LZMA2 dictionary size.Very tiny dictionaries would be a performance problem, so the minimum is 4 KiB.
- See Also:
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DICT_SIZE_MAX
public static final int DICT_SIZE_MAXLargest 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.
- See Also:
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Constructor Details
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LZMA2InputStream
Creates a new input stream that decompresses raw LZMA2 data fromin
.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
- input stream from which LZMA2-compressed data is readdictSize
- LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN
,DICT_SIZE_MAX
]
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LZMA2InputStream
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
- input stream from which LZMA2-compressed data is readdictSize
- LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN
,DICT_SIZE_MAX
]presetDict
- preset dictionary ornull
to use no preset dictionary
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Method Details
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getMemoryUsage
public static int getMemoryUsage(int dictSize) Gets approximate decompressor memory requirements as kibibytes for the given dictionary size.- Parameters:
dictSize
- LZMA2 dictionary size as bytes, must be in the range [DICT_SIZE_MIN
,DICT_SIZE_MAX
]- Returns:
- approximate memory requirements as kibibytes (KiB)
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read
Decompresses the next byte from this input stream.Reading lots of data with
read()
from this input stream may be inefficient. Wrap it injava.io.BufferedInputStream
if you need to read lots of data one byte at a time.- Specified by:
read
in classInputStream
- Returns:
- the next decompressed byte, or
-1
to indicate the end of the compressed stream - Throws:
CorruptedInputException
XZIOException
- if the stream has been closedEOFException
- compressed input is truncated or corruptIOException
- may be thrown byin
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read
Decompresses into an array of bytes.If
len
is zero, no bytes are read and0
is returned. Otherwise this will block untillen
bytes have been decompressed, the end of the LZMA2 stream is reached, or an exception is thrown.- Overrides:
read
in classInputStream
- Parameters:
buf
- target buffer for uncompressed dataoff
- start offset inbuf
len
- maximum number of uncompressed bytes to read- Returns:
- number of bytes read, or
-1
to indicate the end of the compressed stream - Throws:
CorruptedInputException
XZIOException
- if the stream has been closedEOFException
- compressed input is truncated or corruptIOException
- may be thrown byin
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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.- Overrides:
available
in classInputStream
- Returns:
- the number of uncompressed bytes that can be read without blocking
- Throws:
IOException
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close
Closes the stream and callsin.close()
. If the stream was already closed, this does nothing.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classInputStream
- Throws:
IOException
- if thrown byin.close()
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