Package org.apache.commons.compress.harmony.unpack200

Class Segment

java.lang.Object

org.apache.commons.compress.harmony.unpack200.Segment

public class Segment
extends java.lang.Object

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.

Format:

   pack200_archive:
      (pack200_segment)+

   pack200_segment:
      segment_header
      *band_headers :BYTE1
      cp_bands
      attr_definition_bands
      ic_bands
      class_bands
      bc_bands
      file_bands
 

Field Summary

Fields

Modifier and Type	Field	Description
static int	LOG_LEVEL_QUIET	Log level quiet 0
static int	LOG_LEVEL_STANDARD	Log level standard 1
static int	LOG_LEVEL_VERBOSE	Log level verbose 2

Constructor Summary

Constructors

Constructor	Description
Segment()

Method Summary

Modifier and Type	Method	Description
protected AttrDefinitionBands	getAttrDefinitionBands()
protected ClassBands	getClassBands()
SegmentConstantPool	getConstantPool()	Gets the constant pool.
protected CpBands	getCpBands()	Gets the constant pool bands.
protected IcBands	getIcBands()	Gets the inner class bands.
SegmentHeader	getSegmentHeader()	Gets the segment header.
void	log(int messageLevel, java.lang.String message)	Logs a message.
void	overrideDeflateHint(boolean deflateHint)	Overrides the archive's deflate hint with the given boolean
void	setLogLevel(int logLevel)	Sets the log level.
void	setLogStream(java.io.OutputStream logStream)	Sets the log output stream.
void	setPreRead(boolean value)	Sets whether unpacking buffers its input.
void	unpack(java.io.InputStream inputStream, java.util.jar.JarOutputStream out)	Unpacks a packed stream (either .pack.
void	writeJar(java.util.jar.JarOutputStream out)	Writes the segment to an output stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG_LEVEL_VERBOSE

public static final int LOG_LEVEL_VERBOSE

Log level verbose 2

See Also:

Constant Field Values

LOG_LEVEL_STANDARD

public static final int LOG_LEVEL_STANDARD

Log level standard 1

See Also:

Constant Field Values

LOG_LEVEL_QUIET

public static final int LOG_LEVEL_QUIET

Log level quiet 0

See Also:

Constant Field Values

Constructor Detail

Segment

public Segment()

Method Detail

getAttrDefinitionBands

protected AttrDefinitionBands getAttrDefinitionBands()

getClassBands

protected ClassBands getClassBands()

getConstantPool

public SegmentConstantPool getConstantPool()

Gets the constant pool.

Returns:

the constant pool.

getCpBands

protected CpBands getCpBands()

Gets the constant pool bands.

Returns:

the constant pool bands.

getIcBands

protected IcBands getIcBands()

Gets the inner class bands.

Returns:

the inner class bands.

getSegmentHeader

public SegmentHeader getSegmentHeader()

Gets the segment header.

Returns:

the segment header.

log

public void log(int messageLevel,
                java.lang.String message)

Logs a message.

Parameters:

messageLevel - the message level.

message - the message.

overrideDeflateHint

public void overrideDeflateHint(boolean deflateHint)

Overrides the archive's deflate hint with the given boolean

Parameters:

deflateHint - the deflate hint to use

setLogLevel

public void setLogLevel(int logLevel)

Sets the log level.

Parameters:

logLevel - the log level.

setLogStream

public void setLogStream(java.io.OutputStream logStream)

Sets the log output stream.

Parameters:

logStream - log output stream.

setPreRead

public void setPreRead(boolean value)

Sets whether unpacking buffers its input.

Parameters:

value - whether unpacking buffers its input.

unpack

public void unpack(java.io.InputStream inputStream,
                   java.util.jar.JarOutputStream out)
            throws java.io.IOException,
                   Pack200Exception

Unpacks a packed stream (either .pack. or .pack.gz) into a corresponding JarOuputStream.

Parameters:

inputStream - a packed input stream, preferably a BoundedInputStream.

out - output stream.

Throws:

Pack200Exception - if there is a problem unpacking

java.io.IOException - if there is a problem with I/O during unpacking

writeJar

public void writeJar(java.util.jar.JarOutputStream out)
              throws java.io.IOException

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 (for example further segments) to be written.

Parameters:

out - the JarOutputStream to write data to

Throws:

java.io.IOException - if an error occurs while reading or writing to the streams