AsynchronousServerSocketChannel

public abstract class AsynchronousServerSocketChannel extends Object
implements AsynchronousChannel NetworkChannel

An asynchronous channel for stream-oriented listening sockets.

An asynchronous server-socket channel is created by invoking the open method of this class. A newly-created asynchronous server-socket channel is open but not yet bound. It can be bound to a local address and configured to listen for connections by invoking the bind method. Once bound, the accept method is used to initiate the accepting of connections to the channel's socket. An attempt to invoke the accept method on an unbound channel will cause a NotYetBoundException to be thrown.

Channels of this type are safe for use by multiple concurrent threads though at most one accept operation can be outstanding at any time. If a thread initiates an accept operation before a previous accept operation has completed then an AcceptPendingException will be thrown.

Socket options are configured using the setOption method. Channels of this type support the following options:

Option Name Description

SO_RCVBUF The size of the socket receive buffer

SO_REUSEADDR Re-use address

Option Name	Description
`SO_RCVBUF`	The size of the socket receive buffer
`SO_REUSEADDR`	Re-use address

Additional (implementation specific) options may also be supported.

Usage Example:

  final AsynchronousServerSocketChannel listener =
      AsynchronousServerSocketChannel.open().bind(new InetSocketAddress(5000));

  listener.accept(null, new CompletionHandler<AsynchronousSocketChannel,Void>() {
      public void completed(AsynchronousSocketChannel ch, Void att) {
          // accept the next connection
          listener.accept(null, this);

          // handle this connection
          handle(ch);
      }
      public void failed(Throwable exc, Void att) {
          ...
      }
  });

Protected Constructor Summary

AsynchronousServerSocketChannel(AsynchronousChannelProvider provider)

Initializes a new instance of this class.

Public Method Summary

abstract <A> void	accept(A attachment, CompletionHandler<AsynchronousSocketChannel, ? super A> handler) Accepts a connection.
abstract Future<AsynchronousSocketChannel>	accept() Accepts a connection.
abstract AsynchronousServerSocketChannel	bind(SocketAddress local, int backlog) Binds the channel's socket to a local address and configures the socket to listen for connections.
final AsynchronousServerSocketChannel	bind(SocketAddress local) Binds the channel's socket to a local address and configures the socket to listen for connections.
abstract SocketAddress	getLocalAddress() Returns the socket address that this channel's socket is bound to. If there is a security manager set, its `checkConnect` method is called with the local address and `-1` as its arguments to see if the operation is allowed.
static AsynchronousServerSocketChannel	open(AsynchronousChannelGroup group) Opens an asynchronous server-socket channel.
static AsynchronousServerSocketChannel	open() Opens an asynchronous server-socket channel.
final AsynchronousChannelProvider	provider() Returns the provider that created this channel.
abstract <T> AsynchronousServerSocketChannel	setOption(SocketOption<T> name, T value) Sets the value of a socket option.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of `Class` that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

From interface java.nio.channels.AsynchronousChannel

abstract void

close()

Closes this channel.

From interface java.nio.channels.NetworkChannel

abstract NetworkChannel	bind(SocketAddress local) Binds the channel's socket to a local address.
abstract SocketAddress	getLocalAddress() Returns the socket address that this channel's socket is bound to.
abstract <T> T	getOption(SocketOption<T> name) Returns the value of a socket option.
abstract <T> NetworkChannel	setOption(SocketOption<T> name, T value) Sets the value of a socket option.
abstract Set<SocketOption<?>>	supportedOptions() Returns a set of the socket options supported by this channel.

From interface java.nio.channels.Channel

abstract void	close() Closes this channel.
abstract boolean	isOpen() Tells whether or not this channel is open.

From interface java.io.Closeable

abstract void

close()

Closes this stream and releases any system resources associated with it.

From interface java.lang.AutoCloseable

abstract void

close()

Closes this resource, relinquishing any underlying resources.

Protected Constructors

protected AsynchronousServerSocketChannel (AsynchronousChannelProvider provider)

Initializes a new instance of this class.

Parameters

provider	The provider that created this channel

Public Methods

public abstract void accept (A attachment, CompletionHandler<AsynchronousSocketChannel, ? super A> handler)

Accepts a connection.

This method initiates an asynchronous operation to accept a connection made to this channel's socket. The handler parameter is a completion handler that is invoked when a connection is accepted (or the operation fails). The result passed to the completion handler is the AsynchronousSocketChannel to the new connection.

When a new connection is accepted then the resulting AsynchronousSocketChannel will be bound to the same AsynchronousChannelGroup as this channel. If the group is shutdown and a connection is accepted, then the connection is closed, and the operation completes with an IOException and cause ShutdownChannelGroupException.

To allow for concurrent handling of new connections, the completion handler is not invoked directly by the initiating thread when a new connection is accepted immediately (see Threading).

If a security manager has been installed then it verifies that the address and port number of the connection's remote endpoint are permitted by the security manager's checkAccept method. The permission check is performed with privileges that are restricted by the calling context of this method. If the permission check fails then the connection is closed and the operation completes with a SecurityException.

Parameters

attachment	The object to attach to the I/O operation; can be `null`
handler	The handler for consuming the result

Throws

AcceptPendingException	If an accept operation is already in progress on this channel
NotYetBoundException	If this channel's socket has not yet been bound
ShutdownChannelGroupException	If the channel group has terminated

public abstract Future<AsynchronousSocketChannel> accept ()

Accepts a connection.

This method initiates an asynchronous operation to accept a connection made to this channel's socket. The method behaves in exactly the same manner as the accept(Object, CompletionHandler) method except that instead of specifying a completion handler, this method returns a Future representing the pending result. The Future's get method returns the AsynchronousSocketChannel to the new connection on successful completion.

Returns

a Future object representing the pending result

Throws

AcceptPendingException	If an accept operation is already in progress on this channel
NotYetBoundException	If this channel's socket has not yet been bound

public abstract AsynchronousServerSocketChannel bind (SocketAddress local, int backlog)

Binds the channel's socket to a local address and configures the socket to listen for connections.

This method is used to establish an association between the socket and a local address. Once an association is established then the socket remains bound until the associated channel is closed.

The backlog parameter is the maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogther. If the backlog parameter has the value 0, or a negative value, then an implementation specific default is used.

Parameters

local	The local address to bind the socket, or `null` to bind to an automatically assigned socket address
backlog	The maximum number of pending connections

Returns

This channel

Throws

AlreadyBoundException	If the socket is already bound
UnsupportedAddressTypeException	If the type of the given address is not supported
SecurityException	If a security manager has been installed and its `checkListen` method denies the operation
ClosedChannelException	If the channel is closed
IOException	If some other I/O error occurs

public final AsynchronousServerSocketChannel bind (SocketAddress local)

Binds the channel's socket to a local address and configures the socket to listen for connections.

An invocation of this method is equivalent to the following:

 bind(local, 0);

Parameters

local	The local address to bind the socket, or `null` to bind to an automatically assigned socket address

Returns

This channel

Throws

AlreadyBoundException
UnsupportedAddressTypeException
SecurityException
ClosedChannelException
IOException

public abstract SocketAddress getLocalAddress ()

Returns the socket address that this channel's socket is bound to.

Where the channel is bound to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress.

If there is a security manager set, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, a SocketAddress representing the loopback address and the local port of the channel's socket is returned.

Returns

The SocketAddress that the socket is bound to, or the SocketAddress representing the loopback address if denied by the security manager, or null if the channel's socket is not bound

Throws

ClosedChannelException
IOException

public static AsynchronousServerSocketChannel open (AsynchronousChannelGroup group)

Opens an asynchronous server-socket channel.

The new channel is created by invoking the openAsynchronousServerSocketChannel method on the AsynchronousChannelProvider object that created the given group. If the group parameter is null then the resulting channel is created by the system-wide default provider, and bound to the default group.

Parameters

group	The group to which the newly constructed channel should be bound, or `null` for the default group

Returns

A new asynchronous server socket channel

Throws

ShutdownChannelGroupException	If the channel group is shutdown
IOException	If an I/O error occurs

public static AsynchronousServerSocketChannel open ()

Opens an asynchronous server-socket channel.

This method returns an asynchronous server socket channel that is bound to the default group. This method is equivalent to evaluating the expression:

 open((AsynchronousChannelGroup)null);

Returns

A new asynchronous server socket channel

Throws

IOException	If an I/O error occurs

public final AsynchronousChannelProvider provider ()

Returns the provider that created this channel.

Returns

The provider that created this channel

public abstract AsynchronousServerSocketChannel setOption (SocketOption<T> name, T value)

Sets the value of a socket option.

Parameters

name	The socket option
value	The value of the socket option. A value of `null` may be a valid value for some socket options.

Returns

This channel

Throws

IllegalArgumentException
ClosedChannelException
IOException