Module java.base
Package java.nio.channels

Class AsynchronousServerSocketChannel

  • All Implemented Interfaces:
    Closeable, AutoCloseable, AsynchronousChannel, Channel, NetworkChannel
    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:

    Socket 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) {
          ...
      }
  });

    Since:
    1.7

    • Constructor Detail

      • AsynchronousServerSocketChannel

        protected AsynchronousServerSocketChannel​(AsynchronousChannelProvider provider)
        Initializes a new instance of this class.
        Parameters:
        provider - The provider that created this channel

    • Method Detail

      • provider

        public final AsynchronousChannelProvider provider()
        Returns the provider that created this channel.
        Returns:
        The provider that created this channel

      • open

        public static AsynchronousServerSocketChannel open()
                                            throws IOException
        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

      • bind

        public abstract AsynchronousServerSocketChannel bind​(SocketAddress local,
                                                     int backlog)
                                              throws IOException
        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

      • accept

        public abstract <A> 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.

        Type Parameters:
        A - The type of the attachment
        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

      • accept

        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

      • getLocalAddress

        public abstract SocketAddress getLocalAddress()
                                       throws IOException
        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.

        Specified by:
        getLocalAddress in interface NetworkChannel
        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 - If the channel is closed
        IOException - If an I/O error occurs