Module java.base
Package java.nio.channels

Class AsynchronousServerSocketChannel

java.lang.Object
java.nio.channels.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 Details

    • AsynchronousServerSocketChannel

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

  • Method Details

    • provider

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

    • open

      public static AsynchronousServerSocketChannel open​(AsynchronousChannelGroup group) throws IOException
      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

    • 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 final AsynchronousServerSocketChannel bind​(SocketAddress local) throws IOException
      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);
      Specified by:
      bind in interface NetworkChannel
      Parameters:
      local - The local address to bind the socket, or null to bind to an automatically assigned socket address
      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 is installed and it denies an unspecified permission. An implementation of this interface should specify any required permissions.
      ClosedChannelException - If the channel is closed
      IOException - If some other I/O error occurs
      See Also:
      NetworkChannel.getLocalAddress()

    • 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

    • setOption

      public abstract <T> AsynchronousServerSocketChannel setOption​(SocketOption<T> name, T value) throws IOException
      Description copied from interface: NetworkChannel
      Sets the value of a socket option.
      Specified by:
      setOption in interface NetworkChannel
      Type Parameters:
      T - The type of the socket option value
      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 - If the value is not a valid value for this socket option
      ClosedChannelException - If this channel is closed
      IOException - If an I/O error occurs
      See Also:
      StandardSocketOptions

    • 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