org.apache.commons.codec.binary
Class BaseNCodec

java.lang.Object
  org.apache.commons.codec.binary.BaseNCodec

All Implemented Interfaces:

BinaryDecoder, BinaryEncoder, Decoder, Encoder

Direct Known Subclasses:

Base32, Base64

public abstract class BaseNCodec
extends Object
implements BinaryEncoder, BinaryDecoder

Abstract superclass for Base-N encoders and decoders.

This class is thread-safe.

Version:

$Id: BaseNCodec.html 889935 2013-12-11 05:05:13Z ggregory $

Field Summary

protected int	lineLength Chunksize for encoding.
protected static int	MASK_8BITS Mask used to extract 8 bits, used in decoding bytes
static int	MIME_CHUNK_SIZE MIME chunk size per RFC 2045 section 6.8.
protected byte	PAD
protected static byte	PAD_DEFAULT Byte used to pad output.
static int	PEM_CHUNK_SIZE PEM chunk size per RFC 1421 section 4.3.2.4.

Constructor Summary

protected

BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength) Note lineLength is rounded down to the nearest multiple of encodedBlockSize If chunkSeparatorLength is zero, then chunking is disabled.

Method Summary

protected boolean	containsAlphabetOrPad(byte[] arrayOctet) Tests a given byte array to see if it contains any characters within the alphabet or PAD.
byte[]	decode(byte[] pArray) Decodes a byte[] containing characters in the Base-N alphabet.
Object	decode(Object obj) Decodes an Object using the Base-N algorithm.
byte[]	decode(String pArray) Decodes a String containing characters in the Base-N alphabet.
byte[]	encode(byte[] pArray) Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.
Object	encode(Object obj) Encodes an Object using the Base-N algorithm.
String	encodeAsString(byte[] pArray) Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
String	encodeToString(byte[] pArray) Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet.
protected byte[]	ensureBufferSize(int size, org.apache.commons.codec.binary.BaseNCodec.Context context) Ensure that the buffer has room for size bytes
protected int	getDefaultBufferSize() Get the default buffer size.
long	getEncodedLength(byte[] pArray) Calculates the amount of space needed to encode the supplied array.
protected abstract boolean	isInAlphabet(byte value) Returns whether or not the octet is in the current alphabet.
boolean	isInAlphabet(byte[] arrayOctet, boolean allowWSPad) Tests a given byte array to see if it contains only valid characters within the alphabet.
boolean	isInAlphabet(String basen) Tests a given String to see if it contains only valid characters within the alphabet.
protected static boolean	isWhiteSpace(byte byteToCheck) Checks if a byte value is whitespace or not.

Methods inherited from class java.lang.Object

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

Field Detail

MIME_CHUNK_SIZE

public static final int MIME_CHUNK_SIZE

MIME chunk size per RFC 2045 section 6.8.

The 76 character limit does not count the trailing CRLF, but counts all other characters, including any equal signs.

See Also:

RFC 2045 section 6.8, Constant Field Values

PEM_CHUNK_SIZE

public static final int PEM_CHUNK_SIZE

PEM chunk size per RFC 1421 section 4.3.2.4.

The 64 character limit does not count the trailing CRLF, but counts all other characters, including any equal signs.

See Also:

RFC 1421 section 4.3.2.4, Constant Field Values

MASK_8BITS

protected static final int MASK_8BITS

Mask used to extract 8 bits, used in decoding bytes

See Also:

Constant Field Values

PAD_DEFAULT

protected static final byte PAD_DEFAULT

Byte used to pad output.

See Also:

Constant Field Values

PAD

protected final byte PAD

See Also:

Constant Field Values

lineLength

protected final int lineLength

Chunksize for encoding. Not used when decoding. A value of zero or less implies no chunking of the encoded data. Rounded down to nearest multiple of encodedBlockSize.

Constructor Detail

BaseNCodec

protected BaseNCodec(int unencodedBlockSize,
                     int encodedBlockSize,
                     int lineLength,
                     int chunkSeparatorLength)

Note lineLength is rounded down to the nearest multiple of encodedBlockSize If chunkSeparatorLength is zero, then chunking is disabled.

Parameters:

unencodedBlockSize - the size of an unencoded block (e.g. Base64 = 3)

encodedBlockSize - the size of an encoded block (e.g. Base64 = 4)

lineLength - if > 0, use chunking with a length lineLength

chunkSeparatorLength - the chunk separator length, if relevant

Method Detail

getDefaultBufferSize

protected int getDefaultBufferSize()

Get the default buffer size. Can be overridden.

Returns:

DEFAULT_BUFFER_SIZE

ensureBufferSize

protected byte[] ensureBufferSize(int size,
                                  org.apache.commons.codec.binary.BaseNCodec.Context context)

Ensure that the buffer has room for size bytes

Parameters:

size - minimum spare space required

context - the context to be used

isWhiteSpace

protected static boolean isWhiteSpace(byte byteToCheck)

Checks if a byte value is whitespace or not. Whitespace is taken to mean: space, tab, CR, LF

Parameters:

byteToCheck - the byte to check

Returns:

true if byte is whitespace, false otherwise

encode

public Object encode(Object obj)
              throws EncoderException

Encodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].

Specified by:

encode in interface Encoder

Parameters:

obj - Object to encode

Returns:

An object (of type byte[]) containing the Base-N encoded data which corresponds to the byte[] supplied.

Throws:

EncoderException - if the parameter supplied is not of type byte[]

encodeToString

public String encodeToString(byte[] pArray)

Encodes a byte[] containing binary data, into a String containing characters in the Base-N alphabet. Uses UTF8 encoding.

Parameters:

pArray - a byte array containing binary data

Returns:

A String containing only Base-N character data

encodeAsString

public String encodeAsString(byte[] pArray)

Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet. Uses UTF8 encoding.

Parameters:

pArray - a byte array containing binary data

Returns:

String containing only character data in the appropriate alphabet.

decode

public Object decode(Object obj)
              throws DecoderException

Decodes an Object using the Base-N algorithm. This method is provided in order to satisfy the requirements of the Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.

Specified by:

decode in interface Decoder

Parameters:

obj - Object to decode

Returns:

An object (of type byte[]) containing the binary data which corresponds to the byte[] or String supplied.

Throws:

DecoderException - if the parameter supplied is not of type byte[]

decode

public byte[] decode(String pArray)

Decodes a String containing characters in the Base-N alphabet.

Parameters:

pArray - A String containing Base-N character data

Returns:

a byte array containing binary data

decode

public byte[] decode(byte[] pArray)

Decodes a byte[] containing characters in the Base-N alphabet.

Specified by:

decode in interface BinaryDecoder

Parameters:

pArray - A byte array containing Base-N character data

Returns:

a byte array containing binary data

encode

public byte[] encode(byte[] pArray)

Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.

Specified by:

encode in interface BinaryEncoder

Parameters:

pArray - a byte array containing binary data

Returns:

A byte array containing only the basen alphabetic character data

isInAlphabet

protected abstract boolean isInAlphabet(byte value)

Returns whether or not the octet is in the current alphabet. Does not allow whitespace or pad.

Parameters:

value - The value to test

Returns:

true if the value is defined in the current alphabet, false otherwise.

isInAlphabet

public boolean isInAlphabet(byte[] arrayOctet,
                            boolean allowWSPad)

Tests a given byte array to see if it contains only valid characters within the alphabet. The method optionally treats whitespace and pad as valid.

Parameters:

arrayOctet - byte array to test

allowWSPad - if true, then whitespace and PAD are also allowed

Returns:

true if all bytes are valid characters in the alphabet or if the byte array is empty; false, otherwise

isInAlphabet

public boolean isInAlphabet(String basen)

Tests a given String to see if it contains only valid characters within the alphabet. The method treats whitespace and PAD as valid.

Parameters:

basen - String to test

Returns:

true if all characters in the String are valid characters in the alphabet or if the String is empty; false, otherwise

See Also:

isInAlphabet(byte[], boolean)

containsAlphabetOrPad

protected boolean containsAlphabetOrPad(byte[] arrayOctet)

Tests a given byte array to see if it contains any characters within the alphabet or PAD. Intended for use in checking line-ending arrays

Parameters:

arrayOctet - byte array to test

Returns:

true if any byte is a valid character in the alphabet or PAD; false otherwise

getEncodedLength

public long getEncodedLength(byte[] pArray)

Calculates the amount of space needed to encode the supplied array.

Parameters:

pArray - byte[] array which will later be encoded

Returns:

amount of space needed to encoded the supplied array. Returns a long since a max-len array will require > Integer.MAX_VALUE