Package 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:
Base16, Base32, Base64
public abstract class BaseNCodec extends 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.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    BaseNCodec.AbstractBuilder<T,B extends BaseNCodec.AbstractBuilder<T,B>>
    Builds Base64 instances.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    MIME_CHUNK_SIZE
    MIME chunk size per RFC 2045 section 6.8.
    static final int
    PEM_CHUNK_SIZE
    PEM chunk size per RFC 1421 section 4.3.2.4.

  • Method Summary

    Modifier and Type
    Method
    Description
    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.
    byte[]
    encode(byte[] pArray, int offset, int length)
    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.
    static byte[]
    getChunkSeparator()
    Gets a copy of the chunk separator per RFC 2045 section 2.1.
    CodecPolicy
    getCodecPolicy()
    Returns the decoding behavior policy.
    long
    getEncodedLength(byte[] pArray)
    Calculates the amount of space needed to encode the supplied array.
    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.
    boolean
    isStrictDecoding()
    Returns true if decoding behavior is strict.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • 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:

    • 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:

  • Method Details

    • 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:

    • 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

    • 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

    • 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 base N alphabetic character data

    • 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 data
      offset - 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

    • 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[]

    • encodeAsString

      public String encodeAsString(byte[] pArray)
      Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet. Uses UTF8 encoding.

      This is a duplicate of encodeToString(byte[]); it was merged during refactoring.

      Parameters:
      pArray - a byte array containing binary data
      Returns:
      String containing only character data in the appropriate alphabet.
      Since:
      1.5

    • 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

    • 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

    • 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 encode the supplied array. Returns a long since a max-len array will require > Integer.MAX_VALUE

    • 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:

    • isStrictDecoding

      public boolean isStrictDecoding()
      Returns true if decoding behavior is strict. Decoding will raise an IllegalArgumentException 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