Package org.apache.commons.compress.archivers.zip

Class ExplodingInputStream

java.lang.Object

java.io.InputStream

org.apache.commons.compress.archivers.zip.ExplodingInputStream

All Implemented Interfaces:

Closeable, AutoCloseable, InputStreamStatistics

final class ExplodingInputStream
extends InputStream
implements InputStreamStatistics

The implode compression method was added to PKZIP 1.01 released in 1989. It was then dropped from PKZIP 2.0 released in 1993 in favor of the deflate method.

The algorithm is described in the ZIP File Format Specification.

Since:

1.7

See Also:

• ZIP File Format Specification

Field Summary

Fields

Modifier and Type	Field	Description
private BitStream	bits	The stream of bits read from the input stream
private final CircularBuffer	buffer	Output buffer holding the decompressed data
private final int	dictionarySize	The size of the sliding dictionary (4K or 8K)
private BinaryTree	distanceTree	The binary tree containing the 64 encoded distances
private final InputStream	in	The underlying stream containing the compressed data
private BinaryTree	lengthTree	The binary tree containing the 64 encoded lengths
private BinaryTree	literalTree	The binary tree containing the 256 encoded literals (null when only two trees are used)
private final int	minimumMatchLength
private final int	numberOfTrees	The number of Shannon-Fano trees (2 or 3)
private long	treeSizes
private long	uncompressedCount

Constructor Summary

Constructors

Constructor	Description
ExplodingInputStream(int dictionarySize, int numberOfTrees, InputStream in)	Create a new stream decompressing the content of the specified stream using the explode algorithm.

Method Summary

Modifier and Type	Method	Description
void	close()
private void	fillBuffer()	Fill the sliding dictionary with more data.
long	getCompressedCount()	Gets the amount of raw or compressed bytes read by the stream.
long	getUncompressedCount()	Gets the amount of decompressed bytes returned by the stream.
private void	init()	Reads the encoded binary trees and prepares the bit stream.
int	read()

Methods inherited from class java.io.InputStream

available, mark, markSupported, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Details

in

private final InputStream in

The underlying stream containing the compressed data

bits

private BitStream bits

The stream of bits read from the input stream

dictionarySize

private final int dictionarySize

The size of the sliding dictionary (4K or 8K)

numberOfTrees

private final int numberOfTrees

The number of Shannon-Fano trees (2 or 3)

minimumMatchLength

private final int minimumMatchLength

literalTree

private BinaryTree literalTree

The binary tree containing the 256 encoded literals (null when only two trees are used)

lengthTree

private BinaryTree lengthTree

The binary tree containing the 64 encoded lengths

distanceTree

private BinaryTree distanceTree

The binary tree containing the 64 encoded distances

buffer

private final CircularBuffer buffer

Output buffer holding the decompressed data

uncompressedCount

private long uncompressedCount

treeSizes

private long treeSizes

Constructor Details

ExplodingInputStream

public ExplodingInputStream(int dictionarySize,
 int numberOfTrees,
 InputStream in)

Create a new stream decompressing the content of the specified stream using the explode algorithm.

Parameters:

dictionarySize - the size of the sliding dictionary (4096 or 8192)

numberOfTrees - the number of trees (2 or 3)

in - the compressed data stream

Method Details

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

Since:

1.17

fillBuffer

private void fillBuffer()
                 throws IOException

Fill the sliding dictionary with more data.

Throws:

IOException - on error.

getCompressedCount

public long getCompressedCount()

Description copied from interface: InputStreamStatistics

Gets the amount of raw or compressed bytes read by the stream.

Specified by:

getCompressedCount in interface InputStreamStatistics

Returns:

the amount of raw or compressed bytes read by the stream.

Since:

1.17

getUncompressedCount

public long getUncompressedCount()

Description copied from interface: InputStreamStatistics

Gets the amount of decompressed bytes returned by the stream.

Specified by:

getUncompressedCount in interface InputStreamStatistics

Returns:

the amount of decompressed bytes returned by the stream.

Since:

1.17

init

private void init()
           throws IOException

Reads the encoded binary trees and prepares the bit stream.

Throws:

IOException

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException