Communicating Across the Internet - Java 6 - page 465

The following statement creates a Charset object for the ISO-8859-1 character set:

Charset isoset = Charset.forName(“ISO-8859-1”);

After you have a character set object, you can use it to create encoders and decoders. Call
the object's newDecoder() method to create a CharsetDecoder and the newEncoder()
method to create an CharsetEncoder .

To transform a byte buffer into a character buffer, call the decoder's decode( ByteBuffer )
method, which returns a CharBuffer containing the bytes transformed into characters.

To transform a character buffer into a byte buffer, call the encoder's encode( CharBuffer )
method. A ByteBuffer is returned containing the byte values of the characters.

The following statements convert a byte buffer called netBuffer into a character buffer
using the ISO-8859-1 character set:

Charset set = Charset.forName(“ISO-8859-1”);
CharsetDecoder decoder = set.newDecoder();
netBuffer.position(0);
CharBuffer netText = decoder.decode(netBuffer);

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Before the decoder is used to create the character buffer, the call
to position(0) resets the current position of the netBuffer to the
start. When working with buffers for the first time, it's easy to over-
look this, resulting in a buffer with much less data than you
expected.

CAUTION

Channels
A common use for a buffer is to associate it with an input or output stream. You can fill a
buffer with data from an input stream or write a buffer to an output stream.

To do this, you must use a channel , an object that connects a buffer to the stream.
Channels are part of the java.nio.channels package.

Channels can be associated with a stream by calling the getChannel() method available
in some of the stream classes in the java.io package.

The FileInputStream and FileOutputStream classes have getChannel() methods that
return a FileChannel object. This file channel can be used to read, write, and modify the
data in the file.