Package org.apache.commons.codec.binary

Class Base16

java.lang.Object

org.apache.commons.codec.binary.BaseNCodec

org.apache.commons.codec.binary.Base16

All Implemented Interfaces:

BinaryDecoder, BinaryEncoder, Decoder, Encoder

public class Base16
extends BaseNCodec

Provides Base16 encoding and decoding.

This class is thread-safe.

This implementation strictly follows RFC 4648, and as such unlike the Base32 and Base64 implementations, it does not ignore invalid alphabet characters or whitespace, neither does it offer chunking or padding characters.

The only additional feature above those specified in RFC 4648 is support for working with a lower-case alphabet in addition to the default upper-case alphabet.

Since:

1.15

See Also:

• RFC 4648 - 8. Base 16 Encoding

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.commons.codec.binary.BaseNCodec

BaseNCodec.Context

Field Summary

Fields

Modifier and Type	Field	Description
private static final int	BITS_PER_ENCODED_BYTE	BASE16 characters are 4 bits in length.
private static final int	BYTES_PER_ENCODED_BLOCK
private static final int	BYTES_PER_UNENCODED_BLOCK
private final byte[]	decodeTable	Decode table to use.
private final byte[]	encodeTable	Encode table to use.
private static final byte[]	LOWER_CASE_DECODE_TABLE	This array is a lookup table that translates Unicode characters drawn from the a lower-case "Base16 Alphabet" into their 4-bit positive integer equivalents.
private static final byte[]	LOWER_CASE_ENCODE_TABLE	This array is a lookup table that translates 4-bit positive integer index values into their "Base16 Alphabet" lower-case equivalents.
private static final int	MASK_4BITS	Mask used to extract 4 bits, used when decoding character.
private static final byte[]	UPPER_CASE_DECODE_TABLE	This array is a lookup table that translates Unicode characters drawn from the "Base16 Alphabet" (as specified in Table 5 of RFC 4648) into their 4-bit positive integer equivalents.
private static final byte[]	UPPER_CASE_ENCODE_TABLE	This array is a lookup table that translates 4-bit positive integer index values into their "Base16 Alphabet" equivalents as specified in Table 5 of RFC 4648.

Fields inherited from class org.apache.commons.codec.binary.BaseNCodec

CHUNK_SEPARATOR, DECODING_POLICY_DEFAULT, EOF, lineLength, MASK_8BITS, MIME_CHUNK_SIZE, pad, PAD, PAD_DEFAULT, PEM_CHUNK_SIZE

Constructor Summary

Constructors

Constructor	Description
Base16()	Creates a Base16 codec used for decoding and encoding.
Base16(boolean lowerCase)	Creates a Base16 codec used for decoding and encoding.
Base16(boolean lowerCase, CodecPolicy decodingPolicy)	Creates a Base16 codec used for decoding and encoding.

Method Summary

Modifier and Type	Method	Description
(package private) void	decode(byte[] data, int offset, int length, BaseNCodec.Context context)
private int	decodeOctet(byte octet)
(package private) void	encode(byte[] data, int offset, int length, BaseNCodec.Context context)
boolean	isInAlphabet(byte octet)	Returns whether or not the octet is in the Base16 alphabet.
private void	validateTrailingCharacter()	Validates whether decoding allows an entire final trailing character that cannot be used for a complete byte.

Methods inherited from class org.apache.commons.codec.binary.BaseNCodec

available, containsAlphabetOrPad, decode, decode, decode, encode, encode, encode, encodeAsString, encodeToString, ensureBufferSize, getChunkSeparator, getCodecPolicy, getDefaultBufferSize, getEncodedLength, hasData, isInAlphabet, isInAlphabet, isStrictDecoding, isWhiteSpace, readResults

Methods inherited from class java.lang.Object

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

Field Details

BITS_PER_ENCODED_BYTE

private static final int BITS_PER_ENCODED_BYTE

BASE16 characters are 4 bits in length. They are formed by taking an 8-bit group, which is converted into two BASE16 characters.

See Also:

• Constant Field Values

BYTES_PER_ENCODED_BLOCK

private static final int BYTES_PER_ENCODED_BLOCK

See Also:

• Constant Field Values

BYTES_PER_UNENCODED_BLOCK

private static final int BYTES_PER_UNENCODED_BLOCK

See Also:

• Constant Field Values

UPPER_CASE_DECODE_TABLE

private static final byte[] UPPER_CASE_DECODE_TABLE

This array is a lookup table that translates Unicode characters drawn from the "Base16 Alphabet" (as specified in Table 5 of RFC 4648) into their 4-bit positive integer equivalents. Characters that are not in the Base16 alphabet but fall within the bounds of the array are translated to -1.

UPPER_CASE_ENCODE_TABLE

private static final byte[] UPPER_CASE_ENCODE_TABLE

This array is a lookup table that translates 4-bit positive integer index values into their "Base16 Alphabet" equivalents as specified in Table 5 of RFC 4648.

LOWER_CASE_DECODE_TABLE

private static final byte[] LOWER_CASE_DECODE_TABLE

This array is a lookup table that translates Unicode characters drawn from the a lower-case "Base16 Alphabet" into their 4-bit positive integer equivalents. Characters that are not in the Base16 alphabet but fall within the bounds of the array are translated to -1.

LOWER_CASE_ENCODE_TABLE

private static final byte[] LOWER_CASE_ENCODE_TABLE

This array is a lookup table that translates 4-bit positive integer index values into their "Base16 Alphabet" lower-case equivalents.

MASK_4BITS

private static final int MASK_4BITS

Mask used to extract 4 bits, used when decoding character.

See Also:

• Constant Field Values

decodeTable

private final byte[] decodeTable

Decode table to use.

encodeTable

private final byte[] encodeTable

Encode table to use.

Constructor Details

Base16

public Base16()

Creates a Base16 codec used for decoding and encoding.

Base16

public Base16(boolean lowerCase)

Creates a Base16 codec used for decoding and encoding.

Parameters:

lowerCase - if true then use a lower-case Base16 alphabet.

Base16

public Base16(boolean lowerCase,
 CodecPolicy decodingPolicy)

Creates a Base16 codec used for decoding and encoding.

Parameters:

lowerCase - if true then use a lower-case Base16 alphabet.

decodingPolicy - Decoding policy.

Method Details

decode

void decode(byte[] data,
 int offset,
 int length,
 BaseNCodec.Context context)

Specified by:

decode in class BaseNCodec

decodeOctet

private int decodeOctet(byte octet)

encode

void encode(byte[] data,
 int offset,
 int length,
 BaseNCodec.Context context)

Specified by:

encode in class BaseNCodec

isInAlphabet

public boolean isInAlphabet(byte octet)

Returns whether or not the octet is in the Base16 alphabet.

Specified by:

isInAlphabet in class BaseNCodec

Parameters:

octet - The value to test.

Returns:

true if the value is defined in the the Base16 alphabet false otherwise.

validateTrailingCharacter

private void validateTrailingCharacter()

Validates whether decoding allows an entire final trailing character that cannot be used for a complete byte.

Throws:

IllegalArgumentException - if strict decoding is enabled