Class BaseNCodec
- java.lang.Object
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- org.apache.commons.codec.binary.BaseNCodec
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- All Implemented Interfaces:
BinaryDecoder
,BinaryEncoder
,Decoder
,Encoder
public abstract class BaseNCodec extends java.lang.Object implements BinaryEncoder, BinaryDecoder
Abstract superclass for Base-N encoders and decoders.This class is thread-safe.
You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding. These can be bits that are unused from the final character or entire characters. The default mode is lenient decoding.- Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
- Strict: The decoding will raise an
IllegalArgumentException
if trailing bits are not part of a valid encoding. Any unused bits from the final character must be zero. Impossible counts of entire final characters are not allowed.
When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches the original, i.e. no changes occur on the final character. This requires that the input bytes use the same padding and alphabet as the encoder.
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Nested Class Summary
Nested Classes Modifier and Type Class Description (package private) static class
BaseNCodec.Context
Holds thread context so classes can be thread-safe.
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Field Summary
Fields Modifier and Type Field Description (package private) static byte[]
CHUNK_SEPARATOR
Chunk separator per RFC 2045 section 2.1.private int
chunkSeparatorLength
Size of chunk separator.protected static CodecPolicy
DECODING_POLICY_DEFAULT
The default decoding policy.private CodecPolicy
decodingPolicy
Defines the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding.private static int
DEFAULT_BUFFER_RESIZE_FACTOR
private static int
DEFAULT_BUFFER_SIZE
Defines the default buffer size - currently 8192 - must be large enough for at least one encoded block+separatorprivate int
encodedBlockSize
Number of bytes in each full block of encoded data, e.g.(package private) static int
EOF
EOFprotected int
lineLength
Chunksize for encoding.protected static int
MASK_8BITS
Mask used to extract 8 bits, used in decoding bytesprivate static int
MAX_BUFFER_SIZE
The maximum size buffer to allocate.static int
MIME_CHUNK_SIZE
MIME chunk size per RFC 2045 section 6.8.protected byte
pad
protected byte
PAD
Deprecated.Usepad
.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.private int
unencodedBlockSize
Number of bytes in each full block of unencoded data, e.g.
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Constructor Summary
Constructors Modifier Constructor Description protected
BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength)
NotelineLength
is rounded down to the nearest multiple of the encoded block size.protected
BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad)
NotelineLength
is rounded down to the nearest multiple of the encoded block size.protected
BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad, CodecPolicy decodingPolicy)
NotelineLength
is rounded down to the nearest multiple of the encoded block size.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description (package private) int
available(BaseNCodec.Context context)
Returns the amount of buffered data available for reading.private static int
compareUnsigned(int x, int y)
Compares twoint
values numerically treating the values as unsigned.protected boolean
containsAlphabetOrPad(byte[] arrayOctet)
Tests a given byte array to see if it contains any characters within the alphabet or PAD.private static int
createPositiveCapacity(int minCapacity)
Create a positive capacity at least as large the minimum required capacity.byte[]
decode(byte[] pArray)
Decodes a byte[] containing characters in the Base-N alphabet.(package private) abstract void
decode(byte[] pArray, int i, int length, BaseNCodec.Context context)
java.lang.Object
decode(java.lang.Object obj)
Decodes an Object using the Base-N algorithm.byte[]
decode(java.lang.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.byte[]
encode(byte[] pArray, int offset, int length)
Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.(package private) abstract void
encode(byte[] pArray, int i, int length, BaseNCodec.Context context)
java.lang.Object
encode(java.lang.Object obj)
Encodes an Object using the Base-N algorithm.java.lang.String
encodeAsString(byte[] pArray)
Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.java.lang.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, BaseNCodec.Context context)
Ensure that the buffer has room forsize
bytesstatic byte[]
getChunkSeparator()
Gets a copy of the chunk separator per RFC 2045 section 2.1.CodecPolicy
getCodecPolicy()
Returns the decoding behavior policy.protected int
getDefaultBufferSize()
Get the default buffer size.long
getEncodedLength(byte[] pArray)
Calculates the amount of space needed to encode the supplied array.(package private) boolean
hasData(BaseNCodec.Context context)
Returns true if this object has buffered data for reading.protected abstract boolean
isInAlphabet(byte value)
Returns whether or not theoctet
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(java.lang.String basen)
Tests a given String to see if it contains only valid characters within the alphabet.boolean
isStrictDecoding()
Returns true if decoding behavior is strict.protected static boolean
isWhiteSpace(byte byteToCheck)
Checks if a byte value is whitespace or not.(package private) int
readResults(byte[] b, int bPos, int bAvail, BaseNCodec.Context context)
Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail bytes.private static byte[]
resizeBuffer(BaseNCodec.Context context, int minCapacity)
Increases our buffer by theDEFAULT_BUFFER_RESIZE_FACTOR
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Field Detail
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EOF
static final int EOF
EOF- Since:
- 1.7
- See Also:
- Constant Field Values
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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
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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
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DEFAULT_BUFFER_RESIZE_FACTOR
private static final int DEFAULT_BUFFER_RESIZE_FACTOR
- See Also:
- Constant Field Values
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DEFAULT_BUFFER_SIZE
private static final int DEFAULT_BUFFER_SIZE
Defines the default buffer size - currently 8192 - must be large enough for at least one encoded block+separator- See Also:
- Constant Field Values
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MAX_BUFFER_SIZE
private static final int MAX_BUFFER_SIZE
The maximum size buffer to allocate.This is set to the same size used in the JDK
java.util.ArrayList
:Some VMs reserve some header words in an array. Attempts to allocate larger arrays may result in OutOfMemoryError: Requested array size exceeds VM limit.
- See Also:
- Constant Field Values
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MASK_8BITS
protected static final int MASK_8BITS
Mask used to extract 8 bits, used in decoding bytes- See Also:
- Constant Field Values
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PAD_DEFAULT
protected static final byte PAD_DEFAULT
Byte used to pad output.- See Also:
- Constant Field Values
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DECODING_POLICY_DEFAULT
protected static final CodecPolicy DECODING_POLICY_DEFAULT
The default decoding policy.- Since:
- 1.15
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CHUNK_SEPARATOR
static final byte[] CHUNK_SEPARATOR
Chunk separator per RFC 2045 section 2.1.- See Also:
- RFC 2045 section 2.1
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PAD
@Deprecated protected final byte PAD
Deprecated.Usepad
. Will be removed in 2.0.- See Also:
- Constant Field Values
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pad
protected final byte pad
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unencodedBlockSize
private final int unencodedBlockSize
Number of bytes in each full block of unencoded data, e.g. 4 for Base64 and 5 for Base32
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encodedBlockSize
private final int encodedBlockSize
Number of bytes in each full block of encoded data, e.g. 3 for Base64 and 8 for Base32
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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.
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chunkSeparatorLength
private final int chunkSeparatorLength
Size of chunk separator. Not used unlesslineLength
> 0.
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decodingPolicy
private final CodecPolicy decodingPolicy
Defines the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a valid encoding. These can be bits that are unused from the final character or entire characters. The default mode is lenient decoding. Set this totrue
to enable strict decoding.- Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
- Strict: The decoding will raise an
IllegalArgumentException
if trailing bits are not part of a valid encoding. Any unused bits from the final character must be zero. Impossible counts of entire final characters are not allowed.
When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches the original, i.e. no changes occur on the final character. This requires that the input bytes use the same padding and alphabet as the encoder.
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Constructor Detail
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BaseNCodec
protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength)
NotelineLength
is rounded down to the nearest multiple of the encoded block size. IfchunkSeparatorLength
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 lengthlineLength
chunkSeparatorLength
- the chunk separator length, if relevant
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BaseNCodec
protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad)
NotelineLength
is rounded down to the nearest multiple of the encoded block size. IfchunkSeparatorLength
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 lengthlineLength
chunkSeparatorLength
- the chunk separator length, if relevantpad
- byte used as padding byte.
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BaseNCodec
protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad, CodecPolicy decodingPolicy)
NotelineLength
is rounded down to the nearest multiple of the encoded block size. IfchunkSeparatorLength
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 lengthlineLength
chunkSeparatorLength
- the chunk separator length, if relevantpad
- byte used as padding byte.decodingPolicy
- Decoding policy.- Since:
- 1.15
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Method Detail
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compareUnsigned
private static int compareUnsigned(int x, int y)
Compares twoint
values numerically treating the values as unsigned. Taken from JDK 1.8.TODO: Replace with JDK 1.8 Integer::compareUnsigned(int, int).
- Parameters:
x
- the firstint
to comparey
- the secondint
to compare- Returns:
- the value
0
ifx == y
; a value less than0
ifx < y
as unsigned values; and a value greater than0
ifx > y
as unsigned values
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createPositiveCapacity
private static int createPositiveCapacity(int minCapacity)
Create a positive capacity at least as large the minimum required capacity. If the minimum capacity is negative then this throws an OutOfMemoryError as no array can be allocated.- Parameters:
minCapacity
- the minimum capacity- Returns:
- the capacity
- Throws:
java.lang.OutOfMemoryError
- if theminCapacity
is negative
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getChunkSeparator
public static byte[] getChunkSeparator()
Gets a copy of the chunk separator per RFC 2045 section 2.1.- Returns:
- the chunk separator
- Since:
- 1.15
- See Also:
- RFC 2045 section 2.1
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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
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resizeBuffer
private static byte[] resizeBuffer(BaseNCodec.Context context, int minCapacity)
Increases our buffer by theDEFAULT_BUFFER_RESIZE_FACTOR
.- Parameters:
context
- the context to be usedminCapacity
- the minimum required capacity- Returns:
- the resized byte[] buffer
- Throws:
java.lang.OutOfMemoryError
- if theminCapacity
is negative
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available
int available(BaseNCodec.Context context)
Returns the amount of buffered data available for reading.- Parameters:
context
- the context to be used- Returns:
- The amount of buffered data available for reading.
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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
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decode
public byte[] decode(byte[] pArray)
Decodes a byte[] containing characters in the Base-N alphabet.- Specified by:
decode
in interfaceBinaryDecoder
- Parameters:
pArray
- A byte array containing Base-N character data- Returns:
- a byte array containing binary data
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decode
abstract void decode(byte[] pArray, int i, int length, BaseNCodec.Context context)
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decode
public java.lang.Object decode(java.lang.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 interfaceDecoder
- 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[]
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decode
public byte[] decode(java.lang.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
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encode
public byte[] encode(byte[] pArray)
Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.- Specified by:
encode
in interfaceBinaryEncoder
- Parameters:
pArray
- a byte array containing binary data- Returns:
- A byte array containing only the base N alphabetic character data
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encode
public byte[] encode(byte[] pArray, int offset, int length)
Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.- Parameters:
pArray
- a byte array containing binary dataoffset
- initial offset of the subarray.length
- length of the subarray.- Returns:
- A byte array containing only the base N alphabetic character data
- Since:
- 1.11
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encode
abstract void encode(byte[] pArray, int i, int length, BaseNCodec.Context context)
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encode
public java.lang.Object encode(java.lang.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 interfaceEncoder
- 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[]
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encodeAsString
public java.lang.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.
- Since:
- 1.5
This is a duplicate of
encodeToString(byte[])
; it was merged during refactoring.
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encodeToString
public java.lang.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
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ensureBufferSize
protected byte[] ensureBufferSize(int size, BaseNCodec.Context context)
Ensure that the buffer has room forsize
bytes- Parameters:
size
- minimum spare space requiredcontext
- the context to be used- Returns:
- the buffer
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getCodecPolicy
public CodecPolicy getCodecPolicy()
Returns the decoding behavior policy.The default is lenient. If the decoding policy is strict, then decoding will raise an
IllegalArgumentException
if trailing bits are not part of a valid encoding. Decoding will compose trailing bits into 8-bit bytes and discard the remainder.- Returns:
- true if using strict decoding
- Since:
- 1.15
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getDefaultBufferSize
protected int getDefaultBufferSize()
Get the default buffer size. Can be overridden.- Returns:
- the default buffer size.
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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
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hasData
boolean hasData(BaseNCodec.Context context)
Returns true if this object has buffered data for reading.- Parameters:
context
- the context to be used- Returns:
- true if there is data still available for reading.
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isInAlphabet
protected abstract boolean isInAlphabet(byte value)
Returns whether or not theoctet
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.
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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 testallowWSPad
- iftrue
, 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
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isInAlphabet
public boolean isInAlphabet(java.lang.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)
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isStrictDecoding
public boolean isStrictDecoding()
Returns true if decoding behavior is strict. Decoding will raise anIllegalArgumentException
if trailing bits are not part of a valid encoding.The default is false for lenient decoding. Decoding will compose trailing bits into 8-bit bytes and discard the remainder.
- Returns:
- true if using strict decoding
- Since:
- 1.15
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readResults
int readResults(byte[] b, int bPos, int bAvail, BaseNCodec.Context context)
Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail bytes. Returns how many bytes were actually extracted.Package protected for access from I/O streams.
- Parameters:
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).context
- the context to be used- Returns:
- The number of bytes successfully extracted into the provided byte[] array.
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