es.accv.arangi.base.util.base64

Class CharacterDecoder

java.lang.Object

es.accv.arangi.base.util.base64.CharacterDecoder

Direct Known Subclasses:

BASE64Decoder

public abstract class CharacterDecoder
extends java.lang.Object

This class defines the decoding half of character encoders. A character decoder is an algorithim for transforming 8 bit binary data that has been encoded into text by a character encoder, back into original binary form. The character encoders, in general, have been structured around a central theme that binary data can be encoded into text that has the form:

      [Buffer Prefix]
      [Line Prefix][encoded data atoms][Line Suffix]
      [Buffer Suffix]
 

Of course in the simplest encoding schemes, the buffer has no distinct prefix of suffix, however all have some fixed relationship between the text in an 'atom' and the binary data itself. In the CharacterEncoder and CharacterDecoder classes, one complete chunk of data is referred to as a buffer. Encoded buffers are all text, and decoded buffers (sometimes just referred to as buffers) are binary octets. To create a custom decoder, you must, at a minimum, overide three abstract methods in this class.

bytesPerAtom which tells the decoder how many bytes to expect from decodeAtom

decodeAtom which decodes the bytes sent to it as text.

bytesPerLine which tells the encoder the maximum number of bytes per line.

In general, the character decoders return error in the form of a CEFormatException. The syntax of the detail string is

      DecoderClassName: Error message.
 

Several useful decoders have already been written and are referenced in the See Also list below.

Author:

Chuck McManis

See Also:

CEFormatException, CharacterEncoder, UCDecoder, UUDecoder, BASE64Decoder

Constructor Summary

Constructors

Constructor and Description
CharacterDecoder()

Method Summary

Methods

Modifier and Type	Method and Description
byte[]	decodeBuffer(java.io.InputStream in) Decode the contents of the inputstream into a buffer.
void	decodeBuffer(java.io.InputStream aStream, java.io.OutputStream bStream) Decode the text from the InputStream and write the decoded octets to the OutputStream.
byte[]	decodeBuffer(java.lang.String inputString) Alternate decode interface that takes a String containing the encoded buffer and returns a byte array containing the data.
java.nio.ByteBuffer	decodeBufferToByteBuffer(java.io.InputStream in) Decode the contents of the inputStream into a ByteBuffer.
java.nio.ByteBuffer	decodeBufferToByteBuffer(java.lang.String inputString) Decode the contents of the String into a ByteBuffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

CharacterDecoder

public CharacterDecoder()

Method Detail

decodeBuffer

public void decodeBuffer(java.io.InputStream aStream,
                java.io.OutputStream bStream)
                  throws java.io.IOException

Decode the text from the InputStream and write the decoded octets to the OutputStream. This method runs until the stream is exhausted.

Throws:

CEFormatException - An error has occured while decoding

CEStreamExhausted - The input stream is unexpectedly out of data

java.io.IOException

decodeBuffer

public byte[] decodeBuffer(java.lang.String inputString)
                    throws java.io.IOException

Alternate decode interface that takes a String containing the encoded buffer and returns a byte array containing the data.

Throws:

CEFormatException - An error has occured while decoding

java.io.IOException

decodeBuffer

public byte[] decodeBuffer(java.io.InputStream in)
                    throws java.io.IOException

Decode the contents of the inputstream into a buffer.

Throws:

java.io.IOException

decodeBufferToByteBuffer

public java.nio.ByteBuffer decodeBufferToByteBuffer(java.lang.String inputString)
                                             throws java.io.IOException

Decode the contents of the String into a ByteBuffer.

Throws:

java.io.IOException

decodeBufferToByteBuffer

public java.nio.ByteBuffer decodeBufferToByteBuffer(java.io.InputStream in)
                                             throws java.io.IOException

Decode the contents of the inputStream into a ByteBuffer.

Throws:

java.io.IOException