Maven module :un.storage : archive-xz :
Class : un.storage.archive.xz.XZOutputStream
Extends/Implements : un.storage.archive.xz.FinishableOutputStream
Subclasses : -

Compresses into the .xz file format.

Examples



Getting an output stream to compress with LZMA2 using the default
settings and the default integrity check type (CRC64): 


FileOutputStream outfile = new FileOutputStream("foo.xz");

XZOutputStream outxz = new XZOutputStream(outfile, new LZMA2Options());


Using the preset level 8 for LZMA2 (the default
is 6) and SHA-256 instead of CRC64 for integrity checking: 


XZOutputStream outxz = new XZOutputStream(outfile, new LZMA2Options(8),

XZ.CHECK_SHA256);


Using the x86 BCJ filter together with LZMA2 to compress x86 executables
and printing the memory usage information before creating the
XZOutputStream: 


X86Options x86 = new X86Options();

LZMA2Options lzma2 = new LZMA2Options();

FilterOptions[] options = { x86, lzma2 };

System.out.println("Encoder memory usage: "

+ FilterOptions.getEncoderMemoryUsage(options)

+ " KiB");

System.out.println("Decoder memory usage: "

+ FilterOptions.getDecoderMemoryUsage(options)

+ " KiB");

XZOutputStream outxz = new XZOutputStream(outfile, options);


Variables : -
Functions : XZOutputStream, XZOutputStream, XZOutputStream, XZOutputStream, updateFilters, updateFilters, write, write, endBlock, flush, finish, close


Creates a new XZ compressor using one filter and CRC64 as
the integrity check. This constructor is equivalent to passing
a single-member FilterOptions array to
XZOutputStream(OutputStream, FilterOptions[]).

@param out output stream to which the compressed data
will be written

@param filterOptions
filter options to use

@throws UnsupportedOptionsException
invalid filter chain

@throws IOException may be thrown from out
public void XZOutputStream (OutputStream out, FilterOptions filterOptions)


Creates a new XZ compressor using one filter and the specified
integrity check type. This constructor is equivalent to
passing a single-member FilterOptions array to
XZOutputStream(OutputStream, FilterOptions[], int).

@param out output stream to which the compressed data
will be written

@param filterOptions
filter options to use

@param checkType type of the integrity check,
for example XZ.CHECK_CRC32

@throws UnsupportedOptionsException
invalid filter chain

@throws IOException may be thrown from out
public void XZOutputStream (OutputStream out, FilterOptions filterOptions, int checkType)


Creates a new XZ compressor using 1-4 filters and CRC64 as
the integrity check. This constructor is equivalent
XZOutputStream(out, filterOptions, XZ.CHECK_CRC64).

@param out output stream to which the compressed data
will be written

@param filterOptions
array of filter options to use

@throws UnsupportedOptionsException
invalid filter chain

@throws IOException may be thrown from out
public void XZOutputStream (OutputStream out, FilterOptions[] filterOptions)


Creates a new XZ compressor using 1-4 filters and the specified
integrity check type.
param   out output stream to which the compressed data
will be written
param   filterOptions
array of filter options to use
param   checkType type of the integrity check,
for example XZ.CHECK_CRC32
throws   UnsupportedOptionsException
invalid filter chain
throws   IOException may be thrown from out
public void XZOutputStream (OutputStream out, FilterOptions[] filterOptions, int checkType)


Updates the filter chain with a single filter.
This is equivalent to passing a single-member FilterOptions array
to updateFilters(FilterOptions[]).
param   filterOptions
new filter to use
throws   UnsupportedOptionsException
unsupported filter chain, or trying to change
the filter chain in the middle of a Block
public void updateFilters (FilterOptions filterOptions)


Updates the filter chain with 1-4 filters.


Currently this cannot be used to update e.g. LZMA2 options in the
middle of a XZ Block. Use endBlock() to finish the
current XZ Block before calling this function. The new filter chain
will then be used for the next XZ Block.

@param filterOptions
new filter chain to use

@throws UnsupportedOptionsException
unsupported filter chain, or trying to change
the filter chain in the middle of a Block

public void updateFilters (FilterOptions[] filterOptions)


Writes one byte to be compressed.

@throws XZIOException
XZ Stream has grown too big

@throws XZIOException
finish() or close()
was already called

@throws IOException may be thrown by the underlying output stream
public void write (int b)


Writes an array of bytes to be compressed.
The compressors tend to do internal buffering and thus the written
data won't be readable from the compressed output immediately.
Use flush() to force everything written so far to
be written to the underlaying output stream, but be aware that
flushing reduces compression ratio.

@param buf buffer of bytes to be written
@param off start offset in buf
@param len number of bytes to write

@throws XZIOException
XZ Stream has grown too big: total file size
about 8 EiB or the Index field exceeds
16 GiB; you shouldn't reach these sizes
in practice

@throws XZIOException
finish() or close()
was already called and len > 0

@throws IOException may be thrown by the underlying output stream
public void write (byte[] buf, int off, int len)


Finishes the current XZ Block (but not the whole XZ Stream).
This doesn't flush the stream so it's possible that not all data will
be decompressible from the output stream when this function returns.
Call also flush() if flushing is wanted in addition to
finishing the current XZ Block.


If there is no unfinished Block open, this function will do nothing.
(No empty XZ Block will be created.)


This function can be useful, for example, to create
random-accessible .xz files.


Starting a new XZ Block means that the encoder state is reset.
Doing this very often will increase the size of the compressed
file a lot (more than plain flush() would do).

@throws XZIOException
XZ Stream has grown too big

@throws XZIOException
stream finished or closed

@throws IOException may be thrown by the underlying output stream

public void endBlock ()


Flushes the encoder and calls out.flush().
All buffered pending data will then be decompressible from
the output stream.


Calling this function very often may increase the compressed
file size a lot. The filter chain options may affect the size
increase too. For example, with LZMA2 the HC4 match finder has
smaller penalty with flushing than BT4.


Some filters don't support flushing. If the filter chain has
such a filter, flush() will call endBlock()
before flushing.

@throws XZIOException
XZ Stream has grown too big

@throws XZIOException
stream finished or closed

@throws IOException may be thrown by the underlying output stream

public void flush ()


Finishes compression without closing the underlying stream.
No more data can be written to this stream after finishing
(calling write with an empty buffer is OK).


Repeated calls to finish() do nothing unless
an exception was thrown by this stream earlier. In that case
the same exception is thrown again.


After finishing, the stream may be closed normally with
close(). If the stream will be closed anyway, there
usually is no need to call finish() separately.

@throws XZIOException
XZ Stream has grown too big

@throws IOException may be thrown by the underlying output stream

public void finish ()


Finishes compression and closes the underlying stream.
The underlying stream out is closed even if finishing
fails. If both finishing and closing fail, the exception thrown
by finish() is thrown and the exception from the failed
out.close() is lost.

@throws XZIOException
XZ Stream has grown too big

@throws IOException may be thrown by the underlying output stream
public void close ()