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## org.apache.commons.codec.binary
Class BaseNCodec

    java.lang.Object
      org.apache.commons.codec.binary.BaseNCodec

All Implemented Interfaces:
  BinaryDecoder, BinaryEncoder, Decoder, Encoder

Direct Known Subclasses:
  Base32, Base64

    public abstract class BaseNCodec

extends Object
implements BinaryEncoder, BinaryDecoder

Abstract superclass for Base-N encoders and decoders.

This class is thread-safe.

Version:
  $Id: BaseNCodec.java 1382490 2012-09-09 13:10:38Z sebb $

Field Summary
`protected int` | `lineLength` Chunksize for encoding.
`protected static int` | `MASK_8BITS` Mask used to extract 8 bits, used in decoding bytes
`static int` | `MIME_CHUNK_SIZE` MIME chunk size per RFC 2045 section 6.8.
`protected byte` | `PAD`
`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.

Constructor Summary
`protected` | `BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength)` Note `lineLength` is rounded down to the nearest multiple of `encodedBlockSize` If `chunkSeparatorLength` is zero, then chunking is disabled.

Method Summary
`protected boolean` | `containsAlphabetOrPad(byte[] arrayOctet)` Tests a given byte array to see if it contains any characters within the alphabet or PAD.
`byte[]` | `decode(byte[] pArray)` Decodes a byte[] containing characters in the Base-N alphabet.
`Object` | `decode(Object obj)` Decodes an Object using the Base-N algorithm.
`byte[]` | `decode(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.
`Object` | `encode(Object obj)` Encodes an Object using the Base-N algorithm.
`String` | `encodeAsString(byte[] pArray)` Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
`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, org.apache.commons.codec.binary.BaseNCodec.Context context)` Ensure that the buffer has room for `size` bytes
`protected int` | `getDefaultBufferSize()` Get the default buffer size.
`long` | `getEncodedLength(byte[] pArray)` Calculates the amount of space needed to encode the supplied array.
`protected abstract boolean` | `isInAlphabet(byte value)` Returns whether or not the `octet` 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(String basen)` Tests a given String to see if it contains only valid characters within the alphabet.
`protected static boolean` | `isWhiteSpace(byte byteToCheck)` Checks if a byte value is whitespace or not.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### 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

### 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

### MASK_8BITS

    protected static final int MASK_8BITS

  Mask used to extract 8 bits, used in decoding bytes

  See Also:
    Constant Field Values

### PAD_DEFAULT

    protected static final byte PAD_DEFAULT

  Byte used to pad output.

  See Also:
    Constant Field Values

### PAD

    protected final byte PAD

See Also:
  Constant Field Values

### 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.

Constructor Detail

### BaseNCodec

    protected BaseNCodec(int unencodedBlockSize,
                         int encodedBlockSize,
                         int lineLength,
                         int chunkSeparatorLength)

  Note `lineLength` is rounded down to the nearest multiple of `encodedBlockSize` If `chunkSeparatorLength` 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 length `lineLength`
    `chunkSeparatorLength` - the chunk separator length, if relevant

Method Detail

### getDefaultBufferSize

    protected int getDefaultBufferSize()

  Get the default buffer size. Can be overridden.

  Returns:
    `DEFAULT_BUFFER_SIZE`

### ensureBufferSize

    protected byte[] ensureBufferSize(int size,
                                      org.apache.commons.codec.binary.BaseNCodec.Context context)

  Ensure that the buffer has room for `size` bytes

  Parameters:
    `size` - minimum spare space required
    `context` - the context to be used

### 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

### encode

    public Object encode(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 interface `Encoder`
  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[]

### encodeToString

    public 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

### encodeAsString

    public 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.

### decode

    public Object decode(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 interface `Decoder`
  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[]

### decode

    public byte[] decode(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

### decode

    public byte[] decode(byte[] pArray)

  Decodes a byte[] containing characters in the Base-N alphabet.

  Specified by:
    `decode` in interface `BinaryDecoder`
  Parameters:
    `pArray` - A byte array containing Base-N character data
  Returns:
    a byte array containing binary data

### encode

    public byte[] encode(byte[] pArray)

  Encodes a byte[] containing binary data, into a byte[] containing characters in the alphabet.

  Specified by:
    `encode` in interface `BinaryEncoder`
  Parameters:
    `pArray` - a byte array containing binary data
  Returns:
    A byte array containing only the basen alphabetic character data

### isInAlphabet

    protected abstract boolean isInAlphabet(byte value)

  Returns whether or not the `octet` 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.

### 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 test
    `allowWSPad` - if `true`, 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

### isInAlphabet

    public boolean isInAlphabet(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)`

### 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

### 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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