Class Segment
java.lang.Object
org.apache.commons.compress.harmony.unpack200.Segment
A Pack200 archive consists of one or more segments. Each segment is stand-alone, in the sense that every segment has
the magic number header; thus, every segment is also a valid archive. However, it is possible to combine
(non-GZipped) archives into a single large archive by concatenation alone. Thus, all the hard work in unpacking an
archive falls to understanding a segment.
The first component of a segment is the header; this contains (amongst other things) the expected counts of constant
pool entries, which in turn defines how many values need to be read from the stream. Because values are variable
width (see
Codec
), it is not possible to calculate the start of the next segment, although one of the header
values does hint at the size of the segment if non-zero, which can be used for buffering purposes.
Note that this does not perform any buffering of the input stream; each value will be read on a byte-by-byte basis.
It does not perform GZip decompression automatically; both of these are expected to be done by the caller if the
stream has the magic header for GZip streams (GZIPInputStream.GZIP_MAGIC
). In any case, if GZip decompression
is being performed the input stream will be buffered at a higher level, and thus this can read on a byte-oriented
basis.-
Field Summary
FieldsModifier and TypeFieldDescriptionstatic final int
static final int
static final int
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected AttrDefinitionBands
protected ClassBands
protected CpBands
protected IcBands
void
void
overrideDeflateHint
(boolean deflateHint) Override the archive's deflate hint with the given booleanvoid
setLogLevel
(int logLevel) void
setLogStream
(OutputStream logStream) void
setPreRead
(boolean value) void
unpack
(InputStream in, JarOutputStream out) Unpacks a packed stream (either .pack.void
writeJar
(JarOutputStream out) Writes the segment to an output stream.
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Field Details
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LOG_LEVEL_VERBOSE
- See Also:
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LOG_LEVEL_STANDARD
- See Also:
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LOG_LEVEL_QUIET
- See Also:
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Constructor Details
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Segment
public Segment()
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Method Details
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getAttrDefinitionBands
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getClassBands
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getConstantPool
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getCpBands
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getIcBands
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getSegmentHeader
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log
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overrideDeflateHint
Override the archive's deflate hint with the given boolean- Parameters:
deflateHint
- - the deflate hint to use
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setLogLevel
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setLogStream
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setPreRead
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unpack
Unpacks a packed stream (either .pack. or .pack.gz) into a corresponding JarOuputStream.- Parameters:
in
- a packed stream.out
- output stream.- Throws:
Pack200Exception
- if there is a problem unpackingIOException
- if there is a problem with I/O during unpacking
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writeJar
Writes the segment to an output stream. The output stream should be pre-buffered for efficiency. Also takes the same input stream for reading, since the file bits may not be loaded and thus just copied from one stream to another. Doesn't close the output stream when finished, in case there are more entries (e.g. further segments) to be written.- Parameters:
out
- the JarOutputStream to write data to- Throws:
IOException
- if an error occurs while reading or writing to the streams
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