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AsynchronousServerSocketChannel

public abstract class AsynchronousServerSocketChannel
extends Object implements AsynchronousChannel, NetworkChannel

java.lang.Object
   ↳ java.nio.channels.AsynchronousServerSocketChannel


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
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) {
          ...
      }
  });
 

Summary

Protected constructors

AsynchronousServerSocketChannel(AsynchronousChannelProvider provider)

Initializes a new instance of this class.

Public methods

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 methods

Protected constructors

AsynchronousServerSocketChannel

added in API level 26
protected AsynchronousServerSocketChannel (AsynchronousChannelProvider provider)

Initializes a new instance of this class.

Parameters
provider AsynchronousChannelProvider: The provider that created this channel

Public methods

accept

added in API level 26
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 A: The object to attach to the I/O operation; can be null

handler CompletionHandler: 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

accept

added in API level 26
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
Future<AsynchronousSocketChannel> 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

bind

added in API level 26
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 SocketAddress: The local address to bind the socket, or null to bind to an automatically assigned socket address

backlog int: The maximum number of pending connections

Returns
AsynchronousServerSocketChannel 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

bind

added in API level 26
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 SocketAddress: The local address to bind the socket, or null to bind to an automatically assigned socket address

Returns
AsynchronousServerSocketChannel This channel

Throws
AlreadyBoundException
UnsupportedAddressTypeException
SecurityException
ClosedChannelException
IOException

getLocalAddress

added in API level 26
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
SocketAddress 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

open

added in API level 26
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 AsynchronousChannelGroup: The group to which the newly constructed channel should be bound, or null for the default group

Returns
AsynchronousServerSocketChannel A new asynchronous server socket channel

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

open

added in API level 26
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
AsynchronousServerSocketChannel A new asynchronous server socket channel

Throws
IOException If an I/O error occurs

provider

added in API level 26
public final AsynchronousChannelProvider provider ()

Returns the provider that created this channel.

Returns
AsynchronousChannelProvider The provider that created this channel

setOption

added in API level 26
public abstract AsynchronousServerSocketChannel setOption (SocketOption<T> name, 
                T value)

Sets the value of a socket option.

Parameters
name SocketOption: The socket option

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

Returns
AsynchronousServerSocketChannel This channel

Throws
IllegalArgumentException
ClosedChannelException
IOException