Class BaseNCodec

java.lang.Object
org.apache.tomcat.util.codec.binary.BaseNCodec
Direct Known Subclasses:
Base64

public abstract class BaseNCodec extends Object
Abstract superclass for Base-N encoders and decoders.

This class is thread-safe.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final int
    Chunksize for encoding.
    protected static final int
    Mask used to extract 8 bits, used in decoding bytes
    static final int
    MIME chunk size per RFC 2045 section 6.8.
    protected final byte
    Pad byte.
    protected static final byte
    Byte used to pad output.
    protected static final StringManager
     
  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength)
    Note lineLength is rounded down to the nearest multiple of the encoded block size.
    protected
    BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad)
    Note lineLength is rounded down to the nearest multiple of the encoded block size.
  • Method Summary

    Modifier and Type
    Method
    Description
    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.
    byte[]
    decode(byte[] pArray, int off, int len)
     
    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.
    encodeAsString(byte[] pArray)
    Encodes a byte[] containing binary data, into a String containing characters in the appropriate alphabet.
    protected byte[]
    ensureBufferSize(int size, org.apache.tomcat.util.codec.binary.BaseNCodec.Context context)
    Ensure that the buffer has room for size bytes
    protected int
    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.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • sm

      protected static final StringManager sm
    • 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:
    • MASK_8BITS

      protected static final int MASK_8BITS
      Mask used to extract 8 bits, used in decoding bytes
      See Also:
    • PAD_DEFAULT

      protected static final byte PAD_DEFAULT
      Byte used to pad output.
      See Also:
    • pad

      protected final byte pad
      Pad byte. Instance variable just in case it needs to vary later.
    • 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 the nearest multiple of encodedBlockSize.
  • Constructor Details

    • BaseNCodec

      protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength)
      Note lineLength is rounded down to the nearest multiple of the encoded block size. 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
    • BaseNCodec

      protected BaseNCodec(int unencodedBlockSize, int encodedBlockSize, int lineLength, int chunkSeparatorLength, byte pad)
      Note lineLength is rounded down to the nearest multiple of the encoded block size. 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
      pad - byte used as padding byte.
  • Method Details

    • 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
    • decode

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

      public byte[] decode(byte[] pArray, int off, int len)
    • 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.
      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
    • 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.
      Since:
      1.5
    • ensureBufferSize

      protected byte[] ensureBufferSize(int size, org.apache.tomcat.util.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
      Returns:
      the buffer
    • getDefaultBufferSize

      protected int getDefaultBufferSize()
      Get the default buffer size. Can be overridden.
      Returns:
      the default buffer size.
    • 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

      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.