Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

This package is at the heart of the NIO API.
A

channel is a communication channel for
transferring bytes from or to a
java.nio.ByteBuffer. Channels serve a similar
purpose to the InputStream and
OutputStream classes of the
java.io package, but are completely unrelated to
those classes, and provide important features not available with the
java.io API. The Channels class
defines methods that bridge the java.io and
java.nio.channels APIs, by returning channels
based on
streams and streams based on channels.

The
Channel interface simply defines methods
for testing whether a channel is open and for closing a channel. The
other interfaces in the package extend Channel and
define read( ) and write( )
methods for reading bytes from the channel into one or more byte
buffers and for writing bytes from one or more byte buffers to the
channel.

The FileChannel class defines an channel-based API
for reading and writing from files (and also provides other important
file functionality such as file locking and memory mapping that is
not available through the java.io package).
SocketChannel,
ServerSocketChannel, and
DatagramChannel are channels for communication
over a network, and Pipe defines two inner classes
that use the channel abstraction for communication between threads.

The network and pipe channels are all subclasses of the
SelectableChannel class, and may be put into
nonblocking mode, in which calls to read( ) and
write( ) return immediately, even if the channel
is not ready for reading or writing. nonblocking IO and networking is
not possible using the stream abstraction of the
java.io and java.net packages,
and is perhaps the most important new feature of the
java.nio API. The Selector
class is crucial to the efficient use of nonblocking channels: it
allows a program to register interested in I/O operations on several
different channels at once. A call to the select(
) method of a Selector will block until
one of those channels becomes ready for I/O, and will then wake up.
This technique is important for writing scalable high-performance
network servers. See Selector and
SelectionKey for details.

Finally, this package allows for very fine-grained error handling by
defining a large number of exception classes, several of which may be
thrown by only a single method within the java.nio
API.

Interfaces

ByteChannel extends ReadableByteChannel, WritableByteChannel;
public interface

Channel extends java.io.Closeable;
public interface

GatheringByteChannel extends WritableByteChannel;
public interface

InterruptibleChannel extends Channel;
public interface

ReadableByteChannel extends Channel;
public interface

ScatteringByteChannel extends ReadableByteChannel;
public interface

WritableByteChannel extends Channel;

Classes

Channels ;
public abstract class

DatagramChannel extends java.nio.channels.spi.
AbstractSelectableChannel
implements ByteChannel, GatheringByteChannel, ScatteringByteChannel;
public abstract class

FileChannel extends java.nio.channels.spi.
AbstractInterruptibleChannel
implements ByteChannel, GatheringByteChannel, ScatteringByteChannel;
public static class

FileChannel.MapMode ;
public abstract class

FileLock ;
public abstract class

Pipe ;
public abstract static class

Pipe.SinkChannel extends java.nio.channels.spi.
AbstractSelectableChannel
implements GatheringByteChannel, WritableByteChannel;
public abstract static class

Pipe.SourceChannel extends java.nio.channels.spi.
AbstractSelectableChannel
implements ReadableByteChannel, ScatteringByteChannel;
public abstract class

SelectableChannel extends java.nio.channels.spi.
AbstractInterruptibleChannel
implements Channel;
public abstract class

SelectionKey ;
public abstract class

Selector ;
public abstract class

ServerSocketChannel extends java.nio.channels.spi.
AbstractSelectableChannel;
public abstract class

SocketChannel extends java.nio.channels.spi.
AbstractSelectableChannel
implements ByteChannel, GatheringByteChannel, ScatteringByteChannel;

Exceptions

AlreadyConnectedException extends IllegalStateException;
public class

CancelledKeyException extends IllegalStateException;
public class

ClosedChannelException extends java.io.IOException;
public class

AsynchronousCloseException extends ClosedChannelException;
public class

ClosedByInterruptException extends AsynchronousCloseException;
public class

ClosedSelectorException extends IllegalStateException;
public class

ConnectionPendingException extends IllegalStateException;
public class

FileLockInterruptionException extends java.io.IOException;
public class

IllegalBlockingModeException extends IllegalStateException;
public class

IllegalSelectorException extends IllegalArgumentException;
public class

NoConnectionPendingException extends IllegalStateException;
public class

NonReadableChannelException extends IllegalStateException;
public class

NonWritableChannelException extends IllegalStateException;
public class

NotYetBoundException extends IllegalStateException;
public class

NotYetConnectedException extends IllegalStateException;
public class

OverlappingFileLockException extends IllegalStateException;
public class

UnresolvedAddressException extends IllegalArgumentException;
public class

UnsupportedAddressTypeException extends IllegalArgumentException;