ch.rgw.compress
Class HuffmanTree

java.lang.Object
  ch.rgw.compress.HuffmanTree

public class HuffmanTree
extends java.lang.Object

Field Summary

int[]	freq
static byte[]	TextDeutsch Standard table for German text

Constructor Summary

HuffmanTree()

HuffmanTree(byte[] source)
create a Huffman Tree from a given source.

HuffmanTree(int[] frequencyTable)
create a Huffman Tree from a frequency table (which must be an Integer Array of exactly 255 elements)

Method Summary

ch.rgw.compress.HuffmanTree.Node	build(int[] table) Build a tree from a frequency table.
static boolean	checkCompacter()
static int[]	constructTable(byte[] source) constructs a frequency table from an array of bytes
java.io.InputStream	constructTable(java.io.InputStream source, boolean copy) Construct a frequency table from an InputStream.
static int[]	constructTable(java.io.RandomAccessFile file) constructs a frequency table from a file
static boolean	CreateStandardTableFromStream(java.lang.String name, java.io.InputStream in) compute a frequency table from an InputStream and save a compacted representation of this table in the system preferences.
static void	dumpTable(int[] table)
ch.rgw.compress.HuffmanTree.Node	getRootNode()
int[]	getTable()
static int[]	loadTable(java.io.InputStream in) Reloads a frequency table as saved by saveTable
boolean	saveTable(java.io.OutputStream out) Creates a compacted form of the actual frequency table and saves it into an OutputStream.
static int[]	useStandardTable(java.lang.String name) Import a compaced frequency table from the system preferences (In windows from the registry HKLM/JavaSoft/Prefs/ch/rgw/tools/Compress/StandardTables, in Linux from ~/.prefs)
static int[]	useTable(byte[] in) imports a compacted predefined Table
static java.lang.String	Version()

Methods inherited from class java.lang.Object

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

Field Detail

freq

public int[] freq

TextDeutsch

public static byte[] TextDeutsch

Standard table for German text

Constructor Detail

HuffmanTree

public HuffmanTree()

HuffmanTree

public HuffmanTree(byte[] source)

create a Huffman Tree from a given source. Counts the frequency of each byte on the source and constructs the tree accordingly

Parameters:

source - an arbitrary sequence of bytes.

HuffmanTree

public HuffmanTree(int[] frequencyTable)

create a Huffman Tree from a frequency table (which must be an Integer Array of exactly 255 elements)

Parameters:

frequencyTable -

Method Detail

Version

public static java.lang.String Version()

build

public ch.rgw.compress.HuffmanTree.Node build(int[] table)

Build a tree from a frequency table. Ensures that escape and eof are represented in the tree.

Parameters:

table - a field of TABLESIZE ints indicating the frequency od each byte

Returns:

the root node of the newly created tree

constructTable

public static int[] constructTable(byte[] source)

constructs a frequency table from an array of bytes

Parameters:

source - the array to construct the table from

constructTable

public static int[] constructTable(java.io.RandomAccessFile file)

constructs a frequency table from a file

constructTable

public java.io.InputStream constructTable(java.io.InputStream source,
                                          boolean copy)

Construct a frequency table from an InputStream. This will create a temporary file to copy the InputStream in.

Parameters:

source - the Input Stream

Returns:

an InputStream which is a copy of the source Stream, provided to re-Read the same Bytes for the actual compression process.

saveTable

public boolean saveTable(java.io.OutputStream out)

Creates a compacted form of the actual frequency table and saves it into an OutputStream.

Returns:

true on success

loadTable

public static int[] loadTable(java.io.InputStream in)

Reloads a frequency table as saved by saveTable

Returns:

the table

useTable

public static int[] useTable(byte[] in)

imports a compacted predefined Table

Parameters:

in -

Returns:

useStandardTable

public static int[] useStandardTable(java.lang.String name)

Import a compaced frequency table from the system preferences (In windows from the registry HKLM/JavaSoft/Prefs/ch/rgw/tools/Compress/StandardTables, in Linux from ~/.prefs)

Parameters:

name - Name of the table in the registry. If no table with this name is found, the default table (TextDeutsch) is returned.

Returns:

the table

CreateStandardTableFromStream

public static boolean CreateStandardTableFromStream(java.lang.String name,
                                                    java.io.InputStream in)
                                             throws java.lang.Exception

compute a frequency table from an InputStream and save a compacted representation of this table in the system preferences. (To be used later by @see #useStandardTable(String) )

Parameters:

name - name to give the table.

in - InputStream

Returns:

true on success

Throws:

java.lang.Exception

getRootNode

public ch.rgw.compress.HuffmanTree.Node getRootNode()

getTable

public int[] getTable()

dumpTable

public static void dumpTable(int[] table)

checkCompacter

public static boolean checkCompacter()