org.codehaus.plexus.util

Class Base64


public class Base64
extends java.lang.Object

Provides Base64 encoding and decoding as defined by RFC 2045.

This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein.

Version:
$Id: Base64.java 2656 2005-10-11 12:37:02Z brett $
Author:
Apache Software Foundation
Since:
1.0-dev
See Also:
RFC 2045

Field Summary

(package private) static int
BASELENGTH
The base length.
(package private) static byte[]
CHUNK_SEPARATOR
Chunk separator per RFC 2045 section 2.1.
(package private) static int
CHUNK_SIZE
Chunk size per RFC 2045 section 6.8.
(package private) static int
EIGHTBIT
Used to calculate the number of bits in a byte.
(package private) static int
FOURBYTE
Used to get the number of Quadruples.
(package private) static int
LOOKUPLENGTH
Lookup length.
(package private) static byte
PAD
Byte used to pad output.
(package private) static int
SIGN
Used to test the sign of a byte.
(package private) static int
SIXTEENBIT
Used when encoding something which has fewer than 24 bits.
(package private) static int
TWENTYFOURBITGROUP
Used to determine how many bits data contains.
private static byte[]
base64Alphabet
Contains the Base64 values 0 through 63 accessed by using character encodings as indices.
private static byte[]
lookUpBase64Alphabet
Contains the Base64 encodings A through Z, followed by a through z, followed by 0 through 9, followed by +, and /.

Method Summary

byte[]
decode(byte[] pArray)
Decodes a byte[] containing containing characters in the Base64 alphabet.
static byte[]
decodeBase64(byte[] base64Data)
Decodes Base64 data into octects
(package private) static byte[]
discardNonBase64(byte[] data)
Discards any characters outside of the base64 alphabet, per the requirements on page 25 of RFC 2045 - "Any characters outside of the base64 alphabet are to be ignored in base64 encoded data."
(package private) static byte[]
discardWhitespace(byte[] data)
Discards any whitespace from a base-64 encoded block.
byte[]
encode(byte[] pArray)
Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
static byte[]
encodeBase64(byte[] binaryData)
Encodes binary data using the base64 algorithm but does not chunk the output.
static byte[]
encodeBase64(byte[] binaryData, boolean isChunked)
Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
static byte[]
encodeBase64Chunked(byte[] binaryData)
Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
static boolean
isArrayByteBase64(byte[] arrayOctect)
Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
private static boolean
isBase64(byte octect)
Returns whether or not the octect is in the base 64 alphabet.

Field Details

BASELENGTH

(package private) static final int BASELENGTH
The base length.
Field Value:
255

CHUNK_SEPARATOR

(package private) static final byte[] CHUNK_SEPARATOR
Chunk separator per RFC 2045 section 2.1.

CHUNK_SIZE

(package private) static final int CHUNK_SIZE
Chunk size per RFC 2045 section 6.8.

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

Field Value:
76

EIGHTBIT

(package private) static final int EIGHTBIT
Used to calculate the number of bits in a byte.
Field Value:
8

FOURBYTE

(package private) static final int FOURBYTE
Used to get the number of Quadruples.
Field Value:
4

LOOKUPLENGTH

(package private) static final int LOOKUPLENGTH
Lookup length.
Field Value:
64

PAD

(package private) static final byte PAD
Byte used to pad output.
Field Value:
61

SIGN

(package private) static final int SIGN
Used to test the sign of a byte.
Field Value:
-128

SIXTEENBIT

(package private) static final int SIXTEENBIT
Used when encoding something which has fewer than 24 bits.
Field Value:
16

TWENTYFOURBITGROUP

(package private) static final int TWENTYFOURBITGROUP
Used to determine how many bits data contains.
Field Value:
24

base64Alphabet

private static byte[] base64Alphabet
Contains the Base64 values 0 through 63 accessed by using character encodings as indices.

For example, base64Alphabet['+'] returns 62.

The value of undefined encodings is -1.


lookUpBase64Alphabet

private static byte[] lookUpBase64Alphabet
Contains the Base64 encodings A through Z, followed by a through z, followed by 0 through 9, followed by +, and /.

This array is accessed by using character values as indices.

For example, lookUpBase64Alphabet[62] returns '+'.

Method Details

decode

public byte[] decode(byte[] pArray)
Decodes a byte[] containing containing characters in the Base64 alphabet.
Parameters:
pArray - A byte array containing Base64 character data
Returns:
a byte array containing binary data

decodeBase64

public static byte[] decodeBase64(byte[] base64Data)
Decodes Base64 data into octects
Parameters:
base64Data - Byte array containing Base64 data
Returns:
Array containing decoded data.

discardNonBase64

(package private) static byte[] discardNonBase64(byte[] data)
Discards any characters outside of the base64 alphabet, per the requirements on page 25 of RFC 2045 - "Any characters outside of the base64 alphabet are to be ignored in base64 encoded data."
Parameters:
data - The base-64 encoded data to groom
Returns:
The data, less non-base64 characters (see RFC 2045).

discardWhitespace

(package private) static byte[] discardWhitespace(byte[] data)
Discards any whitespace from a base-64 encoded block.
Parameters:
data - The base-64 encoded data to discard the whitespace from.
Returns:
The data, less whitespace (see RFC 2045).

encode

public byte[] encode(byte[] pArray)
Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
Parameters:
pArray - a byte array containing binary data
Returns:
A byte array containing only Base64 character data

encodeBase64

public static byte[] encodeBase64(byte[] binaryData)
Encodes binary data using the base64 algorithm but does not chunk the output.
Parameters:
binaryData - binary data to encode
Returns:
Base64 characters

encodeBase64

public static byte[] encodeBase64(byte[] binaryData,
                                  boolean isChunked)
Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
Parameters:
binaryData - Array containing binary data to encode.
isChunked - if true this encoder will chunk the base64 output into 76 character blocks
Returns:
Base64-encoded data.

encodeBase64Chunked

public static byte[] encodeBase64Chunked(byte[] binaryData)
Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
Parameters:
binaryData - binary data to encode
Returns:
Base64 characters chunked in 76 character blocks

isArrayByteBase64

public static boolean isArrayByteBase64(byte[] arrayOctect)
Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
Parameters:
arrayOctect - byte array to test
Returns:
true if all bytes are valid characters in the Base64 alphabet or if the byte array is empty; false, otherwise

isBase64

private static boolean isBase64(byte octect)
Returns whether or not the octect is in the base 64 alphabet.
Parameters:
octect - The value to test
Returns:
true if the value is defined in the the base 64 alphabet, false otherwise.