public class Base64 extends Object
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.
The class can be parameterized in the following manner with various constructors:
Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
Modifier and Type | Field and Description |
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private byte[] |
buffer
Buffer for streaming.
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(package private) static byte[] |
CHUNK_SEPARATOR
Chunk separator per RFC 2045 section 2.1.
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(package private) static int |
CHUNK_SIZE
Chunk size per RFC 2045 section 6.8.
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private int |
currentLinePos
Variable tracks how many characters have been written to the current line.
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private static byte[] |
DECODE_TABLE
This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
Table 1 of RFC 2045) into their 6-bit positive integer equivalents.
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private int |
decodeSize
Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
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private static int |
DEFAULT_BUFFER_RESIZE_FACTOR |
private static int |
DEFAULT_BUFFER_SIZE |
private int |
encodeSize
Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
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private byte[] |
encodeTable
Encode table to use: either STANDARD or URL_SAFE.
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private boolean |
eof
Boolean flag to indicate the EOF has been reached.
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private int |
lineLength
Line length for encoding.
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private byte[] |
lineSeparator
Line separator for encoding.
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private static int |
MASK_6BITS
Mask used to extract 6 bits, used when encoding
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private static int |
MASK_8BITS
Mask used to extract 8 bits, used in decoding base64 bytes
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private int |
modulus
Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when decoding.
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private static byte |
PAD
Byte used to pad output.
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private int |
pos
Position where next character should be written in the buffer.
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private int |
readPos
Position where next character should be read from the buffer.
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private static byte[] |
STANDARD_ENCODE_TABLE
This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
equivalents as specified in Table 1 of RFC 2045.
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private static byte[] |
URL_SAFE_ENCODE_TABLE
This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
changed to - and _ to make the encoded Base64 results more URL-SAFE.
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private int |
x
Place holder for the 3 bytes we're dealing with for our base64 logic.
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Constructor and Description |
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Base64()
Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
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Base64(boolean urlSafe)
Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
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Base64(int lineLength)
Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
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Base64(int lineLength,
byte[] lineSeparator)
Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
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Base64(int lineLength,
byte[] lineSeparator,
boolean urlSafe)
Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
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Modifier and Type | Method and Description |
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(package private) int |
avail()
Returns the amount of buffered data available for reading.
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private static boolean |
containsBase64Byte(byte[] arrayOctet)
Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
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byte[] |
decode(byte[] pArray)
Decodes a byte[] containing containing characters in the Base64 alphabet.
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(package private) void |
decode(byte[] in,
int inPos,
int inAvail)
Decodes all of the provided data, starting at inPos, for inAvail bytes.
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Object |
decode(Object pObject)
Decodes an Object using the base64 algorithm.
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byte[] |
decode(String pArray)
Decodes a String containing containing characters in the Base64 alphabet.
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static byte[] |
decodeBase64(byte[] base64Data)
Decodes Base64 data into octets
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static byte[] |
decodeBase64(String base64String)
Decodes a Base64 String into octets
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static BigInteger |
decodeInteger(byte[] pArray)
Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
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(package private) static byte[] |
discardWhitespace(byte[] data)
Deprecated.
This method is no longer needed
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byte[] |
encode(byte[] pArray)
Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
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(package private) void |
encode(byte[] in,
int inPos,
int inAvail)
Encodes all of the provided data, starting at inPos, for inAvail bytes.
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Object |
encode(Object pObject)
Encodes an Object using the base64 algorithm.
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static byte[] |
encodeBase64(byte[] binaryData)
Encodes binary data using the base64 algorithm but does not chunk the output.
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static byte[] |
encodeBase64(byte[] binaryData,
boolean isChunked)
Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
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static byte[] |
encodeBase64(byte[] binaryData,
boolean isChunked,
boolean urlSafe)
Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
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static byte[] |
encodeBase64(byte[] binaryData,
boolean isChunked,
boolean urlSafe,
int maxResultSize)
Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
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static byte[] |
encodeBase64Chunked(byte[] binaryData)
Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
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static String |
encodeBase64String(byte[] binaryData)
Encodes binary data using the base64 algorithm into 76 character blocks separated by CRLF.
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static byte[] |
encodeBase64URLSafe(byte[] binaryData)
Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output.
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static String |
encodeBase64URLSafeString(byte[] binaryData)
Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output.
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static byte[] |
encodeInteger(BigInteger bigInt)
Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
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String |
encodeToString(byte[] pArray)
Encodes a byte[] containing binary data, into a String containing characters in the Base64 alphabet.
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private static long |
getEncodeLength(byte[] pArray,
int chunkSize,
byte[] chunkSeparator)
Pre-calculates the amount of space needed to base64-encode the supplied array.
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(package private) boolean |
hasData()
Returns true if this Base64 object has buffered data for reading.
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static boolean |
isArrayByteBase64(byte[] arrayOctet)
Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
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static boolean |
isBase64(byte octet)
Returns whether or not the
octet is in the base 64 alphabet. |
boolean |
isUrlSafe()
Returns our current encode mode.
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private static boolean |
isWhiteSpace(byte byteToCheck)
Checks if a byte value is whitespace or not.
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(package private) int |
readResults(byte[] b,
int bPos,
int bAvail)
Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
bytes.
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private void |
reset()
Resets this Base64 object to its initial newly constructed state.
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private void |
resizeBuffer()
Doubles our buffer.
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(package private) void |
setInitialBuffer(byte[] out,
int outPos,
int outAvail)
Sets the streaming buffer.
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(package private) static byte[] |
toIntegerBytes(BigInteger bigInt)
Returns a byte-array representation of a
BigInteger without sign bit. |
private static final int DEFAULT_BUFFER_RESIZE_FACTOR
private static final int DEFAULT_BUFFER_SIZE
static final int CHUNK_SIZE
The 76 character limit does not count the trailing CRLF, but counts all other characters, including any equal signs.
static final byte[] CHUNK_SEPARATOR
N.B. The next major release may break compatibility and make this field private.
private static final byte[] STANDARD_ENCODE_TABLE
private static final byte[] URL_SAFE_ENCODE_TABLE
private static final byte PAD
private static final byte[] DECODE_TABLE
private static final int MASK_6BITS
private static final int MASK_8BITS
private final byte[] encodeTable
private final int lineLength
private final byte[] lineSeparator
private final int decodeSize
decodeSize = 3 + lineSeparator.length;
private final int encodeSize
encodeSize = 4 + lineSeparator.length;
private byte[] buffer
private int pos
private int readPos
private int currentLinePos
private int modulus
private boolean eof
private int x
public Base64()
When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
When decoding all variants are supported.
public Base64(boolean urlSafe)
When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
When decoding all variants are supported.
urlSafe
- if true
, URL-safe encoding is used. In most cases this should be set to
false
.public Base64(int lineLength)
When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
When decoding all variants are supported.
lineLength
- Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.public Base64(int lineLength, byte[] lineSeparator)
When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
When decoding all variants are supported.
lineLength
- Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.lineSeparator
- Each line of encoded data will end with this sequence of bytes.IllegalArgumentException
- Thrown when the provided lineSeparator included some base64 characters.public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe)
When encoding the line length and line separator are given in the constructor, and the encoding table is STANDARD_ENCODE_TABLE.
Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
When decoding all variants are supported.
lineLength
- Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.lineSeparator
- Each line of encoded data will end with this sequence of bytes.urlSafe
- Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
operations. Decoding seamlessly handles both modes.IllegalArgumentException
- The provided lineSeparator included some base64 characters. That's not going to work!public boolean isUrlSafe()
boolean hasData()
int avail()
private void resizeBuffer()
int readResults(byte[] b, int bPos, int bAvail)
b
- byte[] array to extract the buffered data into.bPos
- position in byte[] array to start extraction at.bAvail
- amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).void setInitialBuffer(byte[] out, int outPos, int outAvail)
out
- byte[] array to buffer directly to.outPos
- Position to start buffering into.outAvail
- Amount of bytes available for direct buffering.void encode(byte[] in, int inPos, int inAvail)
Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last remaining bytes (if not multiple of 3).
Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
in
- byte[] array of binary data to base64 encode.inPos
- Position to start reading data from.inAvail
- Amount of bytes available from input for encoding.void decode(byte[] in, int inPos, int inAvail)
Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1" call is not necessary when decoding, but it doesn't hurt, either.
Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in, garbage-out philosophy: it will not check the provided data for validity.
Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach. http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
in
- byte[] array of ascii data to base64 decode.inPos
- Position to start reading data from.inAvail
- Amount of bytes available from input for encoding.public static boolean isBase64(byte octet)
octet
is in the base 64 alphabet.octet
- The value to testtrue
if the value is defined in the the base 64 alphabet, false
otherwise.public static boolean isArrayByteBase64(byte[] arrayOctet)
arrayOctet
- byte array to testtrue
if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
false, otherwiseprivate static boolean containsBase64Byte(byte[] arrayOctet)
arrayOctet
- byte array to testtrue
if any byte is a valid character in the Base64 alphabet; false herwisepublic static byte[] encodeBase64(byte[] binaryData)
binaryData
- binary data to encodepublic static String encodeBase64String(byte[] binaryData)
binaryData
- binary data to encodepublic static byte[] encodeBase64URLSafe(byte[] binaryData)
binaryData
- binary data to encodepublic static String encodeBase64URLSafeString(byte[] binaryData)
binaryData
- binary data to encodepublic static byte[] encodeBase64Chunked(byte[] binaryData)
binaryData
- binary data to encodepublic Object decode(Object pObject)
pObject
- Object to decodepublic byte[] decode(String pArray)
pArray
- A String containing Base64 character datapublic byte[] decode(byte[] pArray)
pArray
- A byte array containing Base64 character datapublic static byte[] encodeBase64(byte[] binaryData, boolean isChunked)
binaryData
- Array containing binary data to encode.isChunked
- if true
this encoder will chunk the base64 output into 76 character blocksIllegalArgumentException
- Thrown when the input array needs an output array bigger than Integer.MAX_VALUE
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe)
binaryData
- Array containing binary data to encode.isChunked
- if true
this encoder will chunk the base64 output into 76 character blocksurlSafe
- if true
this encoder will emit - and _ instead of the usual + and / characters.IllegalArgumentException
- Thrown when the input array needs an output array bigger than Integer.MAX_VALUE
public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize)
binaryData
- Array containing binary data to encode.isChunked
- if true
this encoder will chunk the base64 output into 76 character blocksurlSafe
- if true
this encoder will emit - and _ instead of the usual + and / characters.maxResultSize
- The maximum result size to accept.IllegalArgumentException
- Thrown when the input array needs an output array bigger than maxResultSizepublic static byte[] decodeBase64(String base64String)
base64String
- String containing Base64 datapublic static byte[] decodeBase64(byte[] base64Data)
base64Data
- Byte array containing Base64 datastatic byte[] discardWhitespace(byte[] data)
data
- The base-64 encoded data to discard the whitespace from.private static boolean isWhiteSpace(byte byteToCheck)
byteToCheck
- the byte to checkpublic Object encode(Object pObject)
pObject
- Object to encodepublic String encodeToString(byte[] pArray)
pArray
- a byte array containing binary datapublic byte[] encode(byte[] pArray)
pArray
- a byte array containing binary dataprivate static long getEncodeLength(byte[] pArray, int chunkSize, byte[] chunkSeparator)
pArray
- byte[] array which will later be encodedchunkSize
- line-length of the output (<= 0 means no chunking) between each
chunkSeparator (e.g. CRLF).chunkSeparator
- the sequence of bytes used to separate chunks of output (e.g. CRLF).public static BigInteger decodeInteger(byte[] pArray)
pArray
- a byte array containing base64 character datapublic static byte[] encodeInteger(BigInteger bigInt)
bigInt
- a BigIntegerNullPointerException
- if null is passed instatic byte[] toIntegerBytes(BigInteger bigInt)
BigInteger
without sign bit.bigInt
- BigInteger
to be convertedprivate void reset()