SocketChannel JDK 1.6)

Description

publicabstract abstract class SocketChannel

A selectable channel for stream-oriented connecting sockets.

Socket channels are not a complete abstraction of connecting network sockets. Binding, shutdown, and the manipulation of socket options must be done through an associated Socket object obtained by invoking the socket method. It is not possible to create a channel for an arbitrary, pre-existing socket, nor is it possible to specify the SocketImpl object to be used by a socket associated with a socket channel.

A socket channel is created by invoking one of the open methods of this class. A newly-created socket channel is open but not yet connected. An attempt to invoke an I/O operation upon an unconnected channel will cause a NotYetConnectedException to be thrown. A socket channel can be connected by invoking its connect method; once connected, a socket channel remains connected until it is closed. Whether or not a socket channel is connected may be determined by invoking its isConnected method.

Socket channels support non-blocking connection: A socket channel may be created and the process of establishing the link to the remote socket may be initiated via the connect method for later completion by the finishConnect method. Whether or not a connection operation is in progress may be determined by invoking the isConnectionPending method.

The input and output sides of a socket channel may independently be shut down without actually closing the channel. Shutting down the input side of a channel by invoking the shutdownInput method of an associated socket object will cause further reads on the channel to return -1, the end-of-stream indication. Shutting down the output side of the channel by invoking the shutdownOutput method of an associated socket object will cause further writes on the channel to throw a ClosedChannelException.

Socket channels support asynchronous shutdown, which is similar to the asynchronous close operation specified in the Channel class. If the input side of a socket is shut down by one thread while another thread is blocked in a read operation on the socket's channel, then the read operation in the blocked thread will complete without reading any bytes and will return -1. If the output side of a socket is shut down by one thread while another thread is blocked in a write operation on the socket's channel, then the blocked thread will receive an AsynchronousCloseException.

Socket channels are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one thread may be reading and at most one thread may be writing at any given time. The connect and finishConnect methods are mutually synchronized against each other, and an attempt to initiate a read or write operation while an invocation of one of these methods is in progress will block until that invocation is complete.

See also:

Methods

Hide/Show inherited methods

protectedfinal void begin () [Inherited From AbstractInterruptibleChannel]

Marks the beginning of an I/O operation that might block indefinitely.

publicfinal Object blockingLock () [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

publicfinal void close () throws IOException [Inherited From AbstractInterruptibleChannel]

Closes this channel.

publicfinal SelectableChannel configureBlocking (boolean block) throws IOException [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

Adjusts this channel's blocking mode.

publicabstract boolean connect (SocketAddress remote) throws IOException

Connects this channel's socket.

protectedfinal void end (boolean completed) throws AsynchronousCloseException [Inherited From AbstractInterruptibleChannel]

Marks the end of an I/O operation that might block indefinitely.

publicabstract boolean finishConnect () throws IOException

Finishes the process of connecting a socket channel.

A non-blocking connection operation is initiated by placing a socket channel in non-blocking mode and then invoking its connect method. Once the connection is established, or the attempt has failed, the socket channel will become connectable and this method may be invoked to complete the connection sequence. If the connection operation failed then invoking this method will cause an appropriate IOException to be thrown.

If this channel is already connected then this method will not block and will immediately return true. If this channel is in non-blocking mode then this method will return false if the connection process is not yet complete. If this channel is in blocking mode then this method will block until the connection either completes or fails, and will always either return true or throw a checked exception describing the failure.

This method may be invoked at any time. If a read or write operation upon this channel is invoked while an invocation of this method is in progress then that operation will first block until this invocation is complete. If a connection attempt fails, that is, if an invocation of this method throws a checked exception, then the channel will be closed.

Returns: true if, and only if, this channel's socket is now connected
Throws:
- NoConnectionPendingException - If this channel is not connected and a connection operation has not been initiated
- ClosedChannelException - If this channel is closed
- AsynchronousCloseException - If another thread closes this channel while the connect operation is in progress
- ClosedByInterruptException - If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt status
- IOException - If some other I/O error occurs

protectedfinal void implCloseChannel () throws IOException [Inherited From AbstractSelectableChannel] [Specified in AbstractInterruptibleChannel]

Closes this channel.

protectedabstract void implCloseSelectableChannel () throws IOException [Inherited From AbstractSelectableChannel]

Closes this selectable channel.

protectedabstract void implConfigureBlocking (boolean block) throws IOException [Inherited From AbstractSelectableChannel]

Adjusts this channel's blocking mode.

publicfinal boolean isBlocking () [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

publicabstract boolean isConnected ()

Tells whether or not this channel's network socket is connected.

publicabstract boolean isConnectionPending ()

Tells whether or not a connection operation is in progress on this channel.

publicfinal boolean isOpen () [Inherited From AbstractInterruptibleChannel]

publicfinal boolean isRegistered () [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

publicfinal SelectionKey keyFor (Selector sel) [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

publicstatic SocketChannel open () throws IOException

Opens a socket channel.

publicstatic SocketChannel open (SocketAddress remote) throws IOException

Opens a socket channel and connects it to a remote address.

publicfinal SelectorProvider provider () [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

Returns the provider that created this channel.

publicabstract int read (ByteBuffer dst) throws IOException

publicfinal long read (ByteBuffer dsts) throws IOException [Specified in ScatteringByteChannel]

publicabstract long read (ByteBuffer dsts, int offset, int length) throws IOException [Specified in ScatteringByteChannel]

publicfinal SelectionKey register (Selector sel, int ops) throws ClosedChannelException [Inherited From SelectableChannel]

Registers this channel with the given selector, returning a selection key.

publicfinal SelectionKey register (Selector sel, int ops, Object att) throws ClosedChannelException [Inherited From AbstractSelectableChannel] [Specified in SelectableChannel]

Registers this channel with the given selector, returning a selection key.

publicabstract Socket socket ()

Retrieves a socket associated with this channel.

publicfinal int validOps () [Specified in SelectableChannel]

Returns an operation set identifying this channel's supported operations.

publicabstract int write (ByteBuffer src) throws IOException

publicfinal long write (ByteBuffer srcs) throws IOException [Specified in GatheringByteChannel]

publicabstract long write (ByteBuffer srcs, int offset, int length) throws IOException [Specified in GatheringByteChannel]