Package ee.jakarta.tck.ws.rs.lib.util
Class CharacterDecoder
java.lang.Object
ee.jakarta.tck.ws.rs.lib.util.CharacterDecoder
- Direct Known Subclasses:
BASE64Decoder
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.
- decodeAtom which decodes the bytes sent to it as text.
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 -
Method Summary
Modifier and TypeMethodDescriptionprotected abstract int
Return the number of bytes per atom of decodingprotected abstract int
Return the maximum number of bytes that can be encoded per lineprotected void
decodeAtom
(PushbackInputStream aStream, OutputStream bStream, int l) This method does an actual decode.byte[]
Decode the contents of the inputstream into a buffer.void
decodeBuffer
(InputStream aStream, OutputStream bStream) Decode the text from the InputStream and write the decoded octets to the OutputStream.byte[]
decodeBuffer
(String inputString) Alternate decode interface that takes a String containing the encoded buffer and returns a byte array containing the data.protected void
decodeBufferPrefix
(PushbackInputStream aStream, OutputStream bStream) decode the beginning of the buffer, by default this is a NOP.protected void
decodeBufferSuffix
(PushbackInputStream aStream, OutputStream bStream) decode the buffer suffix, again by default it is a NOP.Decode the contents of the inputStream into a ByteBuffer.decodeBufferToByteBuffer
(String inputString) Decode the contents of the String into a ByteBuffer.protected int
decodeLinePrefix
(PushbackInputStream aStream, OutputStream bStream) This method should return, if it knows, the number of bytes that will be decoded.protected void
decodeLineSuffix
(PushbackInputStream aStream, OutputStream bStream) This method post processes the line, if there are error detection or correction codes in a line, they are generally processed by this method.protected int
readFully
(InputStream in, byte[] buffer, int offset, int len) This method works around the bizarre semantics of BufferedInputStream's read method.
-
Constructor Details
-
CharacterDecoder
public CharacterDecoder()
-
-
Method Details
-
bytesPerAtom
protected abstract int bytesPerAtom()Return the number of bytes per atom of decoding -
bytesPerLine
protected abstract int bytesPerLine()Return the maximum number of bytes that can be encoded per line -
decodeBufferPrefix
protected void decodeBufferPrefix(PushbackInputStream aStream, OutputStream bStream) throws IOException decode the beginning of the buffer, by default this is a NOP.- Throws:
IOException
-
decodeBufferSuffix
protected void decodeBufferSuffix(PushbackInputStream aStream, OutputStream bStream) throws IOException decode the buffer suffix, again by default it is a NOP.- Throws:
IOException
-
decodeLinePrefix
protected int decodeLinePrefix(PushbackInputStream aStream, OutputStream bStream) throws IOException This method should return, if it knows, the number of bytes that will be decoded. Many formats such as uuencoding provide this information. By default we return the maximum bytes that could have been encoded on the line.- Throws:
IOException
-
decodeLineSuffix
protected void decodeLineSuffix(PushbackInputStream aStream, OutputStream bStream) throws IOException This method post processes the line, if there are error detection or correction codes in a line, they are generally processed by this method. The simplest version of this method looks for the (newline) character.- Throws:
IOException
-
decodeAtom
protected void decodeAtom(PushbackInputStream aStream, OutputStream bStream, int l) throws IOException This method does an actual decode. It takes the decoded bytes and writes them to the OutputStream. The integer l tells the method how many bytes are required. This is always <= bytesPerAtom().- Throws:
IOException
-
readFully
This method works around the bizarre semantics of BufferedInputStream's read method.- Throws:
IOException
-
decodeBuffer
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 decodingCEStreamExhausted
- The input stream is unexpectedly out of dataIOException
-
decodeBuffer
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 decodingIOException
-
decodeBuffer
Decode the contents of the inputstream into a buffer.- Throws:
IOException
-
decodeBufferToByteBuffer
Decode the contents of the String into a ByteBuffer.- Throws:
IOException
-
decodeBufferToByteBuffer
Decode the contents of the inputStream into a ByteBuffer.- Throws:
IOException
-