| Package java.nio.channels | |
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
public interface 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
public final class 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
public class 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; |