org.shlublu.javax.data
Class Base64

java.lang.Object
  |
  +--org.shlublu.javax.data.Base64

public class Base64

extends java.lang.Object

RFC 2045 compliant Base 64 encoder/decoder.

Since:

0.7

Field Summary

static char[]	ENCODING_TABLE The encoding table, according to the RFC.
static char	PAD Metachar, known as PAD in the RFC

Constructor Summary

Base64()

Method Summary

byte[]	decode(char chA, char chB, char chC, char chD) Decoder : take four base 64 digits to produce 1 to 3 bytes, depending the padding chars.
byte[]	decode(java.lang.String strBase64Code) Decoder : take a base 64 string to produce the binary equivalent.
char[]	encode(byte byA) Encoder : take one byte to produce four base 64 digits, the two last ones padded
java.lang.String	encode(byte[] abyData) Encoder : convert the binary given data to a base 64 String.
char[]	encode(byte byA, byte byB) Encoder : take two bytes to produce four base 64 digits, the last one padded
char[]	encode(byte byA, byte byB, byte byC) Encoder : take three bytes to produce four base 64 digits
static int	getBinaryLength(int iCodeLength, int iPadNumber) Return the length of the binary produced for the given base 64 code specs.
static int	getBinaryLength(java.lang.String strCode) Return the length of the binary produced for the given base 64 code.
static int	getCodeLength(byte[] abyToEncode) Return the length of the code produced for the given binary.
static int	getCodeLength(int iBinaryLength) Return the length of the code produced for the given binary length.
static int	getDigitIndex(char ch) Get the given char's correponding index

Methods inherited from class java.lang.Object

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

Field Detail

ENCODING_TABLE

public static final char[] ENCODING_TABLE

The encoding table, according to the RFC. 'A','B','C','D','E','F','G','H', 'I','J','K','L','M','N','O','P', 'Q','R','S','T','U','V','W','X', 'Y','Z','a','b','c','d','e','f', 'g','h','i','j','k','l','m','n', 'o','p','q','r','s','t','u','v', 'w','x','y','z','0','1','2','3', '4','5','6','7','8','9','+','/'

PAD

public static final char PAD

Metachar, known as PAD in the RFC

Constructor Detail

Base64

public Base64()

Method Detail

getCodeLength

public static final int getCodeLength(byte[] abyToEncode)

Return the length of the code produced for the given binary. Length dedicated to the CRLF insertions is included.

Parameters:

abyToEncode - The binary to encode

Returns:

int the implied length

getCodeLength

public static final int getCodeLength(int iBinaryLength)

Return the length of the code produced for the given binary length. Length dedicated to the CRLF insertions is included.

Parameters:

abyToEncode - The binary to encode

Returns:

int the implied length

getBinaryLength

public static final int getBinaryLength(java.lang.String strCode)
                                 throws TruncatedBase64CodeException,
                                        UnexpectedPadException

Return the length of the binary produced for the given base 64 code. The code is assumed as clean, the LFs and CRs are silentely ignored.

Parameters:

strCode - The base 64 code

Returns:

int the implied length

Throws:

TruncatedBase64CodeException - if the code length is not a multiple of 4

UnexpectedPadException - if ththis code contains more than 2 PADs

getBinaryLength

public static int getBinaryLength(int iCodeLength,
                                  int iPadNumber)
                           throws TruncatedBase64CodeException,
                                  UnexpectedPadException

Return the length of the binary produced for the given base 64 code specs.

Parameters:

iCodeLength - A code length, without CR/LFs

iPadNumber - The number of padding char in this code E [0;2]

Returns:

int the implied length

Throws:

TruncatedBase64CodeException - if the code length is not a multiple of 4

UnexpectedPadException - if the pad number is not E [0;2]

encode

public final java.lang.String encode(byte[] abyData)

Encoder : convert the binary given data to a base 64 String.
According to the RFC 2045, the output is a set of lines of 76 character each.

Parameters:

byte - [] abyData The binary data to encode

Returns:

String The base 64 corresponding code, as a String obtained by new String(internal char buffer). So there's an array copy

See Also:

String.String(char[])

encode

public final char[] encode(byte byA,
                           byte byB,
                           byte byC)

Encoder : take three bytes to produce four base 64 digits

Parameters:

byte - The bytes to encode

Returns:

char[4] The base 64 corresponding digits.

encode

public final char[] encode(byte byA,
                           byte byB)

Encoder : take two bytes to produce four base 64 digits, the last one padded

Parameters:

byte - The bytes to encode

Returns:

char[4] The base 64 corresponding digits.

encode

public final char[] encode(byte byA)

Encoder : take one byte to produce four base 64 digits, the two last ones padded

Parameters:

byte - The byte to encode

Returns:

char[4] The base 64 corresponding digits.

decode

public final byte[] decode(java.lang.String strBase64Code)
                    throws UnknownBase64DigitException,
                           UnexpectedPadException,
                           TruncatedBase64CodeException

Decoder : take a base 64 string to produce the binary equivalent. The line breaks contained in the string are ignored (LF and so CR) silentely.

Parameters:

strBase64Code - The digits to decode

Returns:

byte[] The corresponding bytes.

Throws:

UnknownBase64DigitException - if one at least of the given chars is not PAD and is unknown in the encoding table.

UnexpectedPadException - if a padding char is found at an unexpected position.

TruncatedBase64CodeException - if the given code is not multiple of 4 chars

decode

public final byte[] decode(char chA,
                           char chB,
                           char chC,
                           char chD)
                    throws UnknownBase64DigitException,
                           UnexpectedPadException

Decoder : take four base 64 digits to produce 1 to 3 bytes, depending the padding chars.

Parameters:

char - The digits to decode

Returns:

byte[1 to 3] The corresponding bytes.

Throws:

UnknownBase64DigitException - if one at least of the given chars is not PAD and is unknown in the encoding table.

UnexpectedPadException - if a padding char is found in the two firsts digits, or in third position without having a padding fourth digit.

getDigitIndex

public static final int getDigitIndex(char ch)
                               throws UnknownBase64DigitException

Get the given char's correponding index

Parameters:

char - ch A base 64 digit, or PAD

Returns:

int The ENCODING_TABLE index e [0;63] of the given char, -1 if PAD

Throws:

UnknownBase64DigitException - if the given char is not PAD and unknown in the encoding table.