org.apache.river.jeri.internal.runtime

Class CharacterEncoder

java.lang.Object

org.apache.river.jeri.internal.runtime.CharacterEncoder

Direct Known Subclasses:

BASE64Encoder, HexDumpEncoder

public abstract class CharacterEncoder
extends Object

This class defines the encoding half of character encoders. A character encoder is an algorithm for transforming 8 bit binary data into text (generally 7 bit ASCII or 8 bit ISO-Latin-1 text) for transmission over text channels such as e-mail and network news. The character encoders have been structured around a central theme that, in general, the encoded text has the form:

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

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 encoder, you must, at a minimum, override three abstract methods in this class.

bytesPerAtom which tells the encoder how many bytes to send to encodeAtom

encodeAtom which encodes the bytes sent to it as text.

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

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

Author:

Sun Microsystems, Inc.

Field Summary

Fields

Modifier and Type	Field and Description
protected PrintStream	pStream Stream that understands "printing"

Constructor Summary

Constructors

Constructor and Description
CharacterEncoder()

Method Summary

Modifier and Type	Method and Description
protected abstract int	bytesPerAtom() Return the number of bytes per atom of encoding
protected abstract int	bytesPerLine() Return the number of bytes that can be encoded per line
String	encode(byte[] aBuffer) A 'streamless' version of encode that simply takes a buffer of bytes and returns a string containing the encoded buffer.
void	encode(byte[] aBuffer, OutputStream aStream) Encode the buffer in aBuffer and write the encoded result to the OutputStream aStream.
void	encode(InputStream inStream, OutputStream outStream) Encode bytes from the input stream, and write them as text characters to the output stream.
protected abstract void	encodeAtom(OutputStream aStream, byte[] someBytes, int anOffset, int aLength) Encode one "atom" of information into characters.
String	encodeBuffer(byte[] aBuffer) A 'streamless' version of encode that simply takes a buffer of bytes and returns a string containing the encoded buffer.
void	encodeBuffer(byte[] aBuffer, OutputStream aStream) Encode the buffer in aBuffer and write the encoded result to the OutputStream aStream.
void	encodeBuffer(InputStream inStream, OutputStream outStream) Encode bytes from the input stream, and write them as text characters to the output stream.
protected void	encodeBufferPrefix(OutputStream aStream) Encode the prefix for the entire buffer.
protected void	encodeBufferSuffix(OutputStream aStream) Encode the suffix for the entire buffer.
protected void	encodeLinePrefix(OutputStream aStream, int aLength) Encode the prefix that starts every output line.
protected void	encodeLineSuffix(OutputStream aStream) Encode the suffix that ends every output line.
protected int	readFully(InputStream in, byte[] buffer) This method works around the bizarre semantics of BufferedInputStream's read method.

Methods inherited from class java.lang.Object

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

Field Detail

pStream

protected PrintStream pStream

Stream that understands "printing"

Constructor Detail

CharacterEncoder

public CharacterEncoder()

Method Detail

bytesPerAtom

protected abstract int bytesPerAtom()

Return the number of bytes per atom of encoding

bytesPerLine

protected abstract int bytesPerLine()

Return the number of bytes that can be encoded per line

encodeBufferPrefix

protected void encodeBufferPrefix(OutputStream aStream)
                           throws IOException

Encode the prefix for the entire buffer. By default is simply opens the PrintStream for use by the other functions.

Throws:

IOException

encodeBufferSuffix

protected void encodeBufferSuffix(OutputStream aStream)
                           throws IOException

Encode the suffix for the entire buffer.

Throws:

IOException

encodeLinePrefix

protected void encodeLinePrefix(OutputStream aStream,
                                int aLength)
                         throws IOException

Encode the prefix that starts every output line.

Throws:

IOException

encodeLineSuffix

protected void encodeLineSuffix(OutputStream aStream)
                         throws IOException

Encode the suffix that ends every output line. By default this method just prints a newline into the output stream.

Throws:

IOException

encodeAtom

protected abstract void encodeAtom(OutputStream aStream,
                                   byte[] someBytes,
                                   int anOffset,
                                   int aLength)
                            throws IOException

Encode one "atom" of information into characters.

Throws:

IOException

readFully

protected int readFully(InputStream in,
                        byte[] buffer)
                 throws IOException

This method works around the bizarre semantics of BufferedInputStream's read method.

Throws:

IOException

encode

public void encode(InputStream inStream,
                   OutputStream outStream)
            throws IOException

Encode bytes from the input stream, and write them as text characters to the output stream. This method will run until it exhausts the input stream, but does not print the line suffix for a final line that is shorter than bytesPerLine().

Throws:

IOException

encode

public void encode(byte[] aBuffer,
                   OutputStream aStream)
            throws IOException

Encode the buffer in aBuffer and write the encoded result to the OutputStream aStream.

Throws:

IOException

encode

public String encode(byte[] aBuffer)

A 'streamless' version of encode that simply takes a buffer of bytes and returns a string containing the encoded buffer.

encodeBuffer

public void encodeBuffer(InputStream inStream,
                         OutputStream outStream)
                  throws IOException

Encode bytes from the input stream, and write them as text characters to the output stream. This method will run until it exhausts the input stream. It differs from encode in that it will add the line at the end of a final line that is shorter than bytesPerLine().

Throws:

IOException

encodeBuffer

public void encodeBuffer(byte[] aBuffer,
                         OutputStream aStream)
                  throws IOException

Encode the buffer in aBuffer and write the encoded result to the OutputStream aStream.

Throws:

IOException

encodeBuffer

public String encodeBuffer(byte[] aBuffer)
                    throws UnsupportedEncodingException

A 'streamless' version of encode that simply takes a buffer of bytes and returns a string containing the encoded buffer.

Throws:

UnsupportedEncodingException