org.cryptacular.codec

Class AbstractBaseNEncoder

java.lang.Object

org.cryptacular.codec.AbstractBaseNEncoder

All Implemented Interfaces:

Encoder

Direct Known Subclasses:

Base32Encoder, Base64Encoder

public abstract class AbstractBaseNEncoder
extends Object
implements Encoder

Base encoder class for encoding schemes described in RFC 3548.

Author:

Middleware Services

Field Summary

Fields

Modifier and Type	Field and Description
protected int	lineLength Number of base64 characters per line.

Constructor Summary

Constructors

Constructor and Description
AbstractBaseNEncoder(char[] characterSet, int charactersPerLine) Creates a new instance with given parameters.

Method Summary

Modifier and Type	Method and Description
void	encode(ByteBuffer input, CharBuffer output) Encodes bytes in input buffer into characters placed in the output buffer.
protected static char[]	encodingTable(String alphabet, int n) Converts the given alphabet into a base-N encoding table.
void	finalize(CharBuffer output) Performs final output encoding (e.g. padding) after all input bytes have been provided.
protected abstract int	getBitsPerChar()
protected abstract int	getBlockLength()
boolean	isPaddedOutput()
int	outputSize(int inputSize) Expected number of characters in the output buffer for an input buffer of the given size.
void	setPaddedOutput(boolean enabled) Sets the output padding mode.

Methods inherited from class java.lang.Object

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

Field Detail

lineLength

protected final int lineLength

Number of base64 characters per line.

Constructor Detail

AbstractBaseNEncoder

public AbstractBaseNEncoder(char[] characterSet,
                            int charactersPerLine)

Creates a new instance with given parameters.

Parameters:

characterSet - Encoding character set.

charactersPerLine - Number of characters per line.

Method Detail

isPaddedOutput

public boolean isPaddedOutput()

Returns:

True if padded output is enabled (default), false otherwise.

setPaddedOutput

public void setPaddedOutput(boolean enabled)

Sets the output padding mode.

Parameters:

enabled - True to enable padded output, false otherwise.

encode

public void encode(ByteBuffer input,
                   CharBuffer output)
            throws EncodingException

Description copied from interface: Encoder

Encodes bytes in input buffer into characters placed in the output buffer. This method may be called multiple times, followed by Encoder.finalize(java.nio.CharBuffer) after all input bytes have been provided.

Specified by:

encode in interface Encoder

Parameters:

input - Input byte buffer.

output - Output character buffer.

Throws:

EncodingException - on encoding errors.

finalize

public void finalize(CharBuffer output)
              throws EncodingException

Description copied from interface: Encoder

Performs final output encoding (e.g. padding) after all input bytes have been provided.

Specified by:

finalize in interface Encoder

Parameters:

output - Output character buffer.

Throws:

EncodingException - on encoding errors.

outputSize

public int outputSize(int inputSize)

Description copied from interface: Encoder

Expected number of characters in the output buffer for an input buffer of the given size.

Specified by:

outputSize in interface Encoder

Parameters:

inputSize - Size of input buffer in bytes.

Returns:

Minimum character buffer size required to store all encoded input bytes.

getBlockLength

protected abstract int getBlockLength()

Returns:

Number of bits in a block of encoded characters.

getBitsPerChar

protected abstract int getBitsPerChar()

Returns:

Number of bits encoding a single character.

encodingTable

protected static char[] encodingTable(String alphabet,
                                      int n)

Converts the given alphabet into a base-N encoding table.

Parameters:

alphabet - Encoding alphabet to use.

n - Encoding base.

Returns:

Encoding table of N elements.