https://openjdk.java.net/ 
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package java.nio.channels;

import java.nio.channels.spi.*;
import java.net.SocketOption;
import java.net.SocketAddress;
import java.util.concurrent.Future;
import java.io.IOException;


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
/**
 * An asynchronous channel for stream-oriented listening sockets.
 *
 * <p> An asynchronous server-socket channel is created by invoking the
 * {@link #open 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 {@link #bind(SocketAddress,int) bind} method. Once bound,
 * the {@link #accept(Object,CompletionHandler) accept} method
 * is used to initiate the accepting of connections to the channel's socket.
 * An attempt to invoke the {@code accept} method on an unbound channel will
 * cause a {@link NotYetBoundException} to be thrown.
 *
 * <p> 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 {@link AcceptPendingException} will be thrown.
 *
 * <p> Socket options are configured using the {@link #setOption(SocketOption,Object)
 * setOption} method. Channels of this type support the following options:
 * <blockquote>
 * <table class="striped">
 * <caption style="display:none">Socket options</caption>
 * <thead>
 *   <tr>
 *     <th scope="col">Option Name</th>
 *     <th scope="col">Description</th>
 *   </tr>
 * </thead>
 * <tbody>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} </th>
 *     <td> The size of the socket receive buffer </td>
 *   </tr>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} </th>
 *     <td> Re-use address </td>
 *   </tr>
 * </tbody>
 * </table>
 * </blockquote>
 * Additional (implementation specific) options may also be supported.
 *
 * <p> <b>Usage Example:</b>
 * <pre>
 *  final AsynchronousServerSocketChannel listener =
 *      AsynchronousServerSocketChannel.open().bind(new InetSocketAddress(5000));
 *
 *  listener.accept(null, new CompletionHandler&lt;AsynchronousSocketChannel,Void&gt;() {
 *      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) {
 *          ...
 *      }
 *  });
 * </pre>
 *
 * @since 1.7
 */

public abstract class AsynchronousServerSocketChannel
    implements AsynchronousChannel, NetworkChannel
{
    private final AsynchronousChannelProvider provider;

    
Initializes a new instance of this class.

Params:
  • provider – 
        The provider that created this channel
/**
     * Initializes a new instance of this class.
     *
     * @param  provider
     *         The provider that created this channel
     */
    protected AsynchronousServerSocketChannel(AsynchronousChannelProvider provider) {
        this.provider = provider;
    }

    
Returns the provider that created this channel.

Returns: The provider that created this channel
/**
     * Returns the provider that created this channel.
     *
     * @return  The provider that created this channel
     */
    public final AsynchronousChannelProvider provider() {
        return provider;
    }

    
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.

Params:
  • group –  The group to which the newly constructed channel should be bound, or null for the default group
Throws:
Returns: A new asynchronous server socket channel
/**
     * Opens an asynchronous server-socket channel.
     *
     * <p> The new channel is created by invoking the {@link
     * java.nio.channels.spi.AsynchronousChannelProvider#openAsynchronousServerSocketChannel
     * openAsynchronousServerSocketChannel} method on the {@link
     * java.nio.channels.spi.AsynchronousChannelProvider} object that created
     * the given group. If the group parameter is {@code null} then the
     * resulting channel is created by the system-wide default provider, and
     * bound to the <em>default group</em>.
     *
     * @param   group
     *          The group to which the newly constructed channel should be bound,
     *          or {@code null} for the default group
     *
     * @return  A new asynchronous server socket channel
     *
     * @throws  ShutdownChannelGroupException
     *          If the channel group is shutdown
     * @throws  IOException
     *          If an I/O error occurs
     */
    public static AsynchronousServerSocketChannel open(AsynchronousChannelGroup group)
        throws IOException
    {
        AsynchronousChannelProvider provider = (group == null) ?
            AsynchronousChannelProvider.provider() : group.provider();
        return provider.openAsynchronousServerSocketChannel(group);
    }

    
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);



Throws:
Returns: A new asynchronous server socket channel
/**
     * Opens an asynchronous server-socket channel.
     *
     * <p> This method returns an asynchronous server socket channel that is
     * bound to the <em>default group</em>. This method is equivalent to evaluating
     * the expression:
     * <blockquote><pre>
     * open((AsynchronousChannelGroup)null);
     * </pre></blockquote>
     *
     * @return  A new asynchronous server socket channel
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    public static AsynchronousServerSocketChannel open()
        throws IOException
    {
        return open(null);
    }

    
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);



Params:
  • local –  The local address to bind the socket, or null to bind to an automatically assigned socket address
Throws:
Returns: This channel
/**
     * Binds the channel's socket to a local address and configures the socket to
     * listen for connections.
     *
     * <p> An invocation of this method is equivalent to the following:
     * <blockquote><pre>
     * bind(local, 0);
     * </pre></blockquote>
     *
     * @param   local
     *          The local address to bind the socket, or {@code null} to bind
     *          to an automatically assigned socket address
     *
     * @return  This channel
     *
     * @throws  AlreadyBoundException               {@inheritDoc}
     * @throws  UnsupportedAddressTypeException     {@inheritDoc}
     * @throws  SecurityException                   {@inheritDoc}
     * @throws  ClosedChannelException              {@inheritDoc}
     * @throws  IOException                         {@inheritDoc}
     */
    public final AsynchronousServerSocketChannel bind(SocketAddress local)
        throws IOException
    {
        return bind(local, 0);
    }

    
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. 
Params:
  • 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
Throws:
Returns: This channel
/**
     * Binds the channel's socket to a local address and configures the socket to
     * listen for connections.
     *
     * <p> 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.
     *
     * <p> The {@code 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 {@code backlog} parameter has
     * the value {@code 0}, or a negative value, then an implementation specific
     * default is used.
     *
     * @param   local
     *          The local address to bind the socket, or {@code null} to bind
     *          to an automatically assigned socket address
     * @param   backlog
     *          The maximum number of pending connections
     *
     * @return  This channel
     *
     * @throws  AlreadyBoundException
     *          If the socket is already bound
     * @throws  UnsupportedAddressTypeException
     *          If the type of the given address is not supported
     * @throws  SecurityException
     *          If a security manager has been installed and its {@link
     *          SecurityManager#checkListen checkListen} method denies the operation
     * @throws  ClosedChannelException
     *          If the channel is closed
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract AsynchronousServerSocketChannel bind(SocketAddress local, int backlog)
        throws IOException;

    
Throws:
/**
     * @throws  IllegalArgumentException                {@inheritDoc}
     * @throws  ClosedChannelException                  {@inheritDoc}
     * @throws  IOException                             {@inheritDoc}
     */
    public abstract <T> AsynchronousServerSocketChannel setOption(SocketOption<T> name, T value)
        throws IOException;

    
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. 
Params:
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
/**
     * Accepts a connection.
     *
     * <p> This method initiates an asynchronous operation to accept a
     * connection made to this channel's socket. The {@code 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 {@link AsynchronousSocketChannel} to the new connection.
     *
     * <p> When a new connection is accepted then the resulting {@code
     * AsynchronousSocketChannel} will be bound to the same {@link
     * AsynchronousChannelGroup} as this channel. If the group is {@link
     * AsynchronousChannelGroup#isShutdown shutdown} and a connection is accepted,
     * then the connection is closed, and the operation completes with an {@code
     * IOException} and cause {@link ShutdownChannelGroupException}.
     *
     * <p> 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 <a
     * href="AsynchronousChannelGroup.html#threading">Threading</a>).
     *
     * <p> 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 {@link SecurityManager#checkAccept 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 {@link
     * SecurityException}.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   attachment
     *          The object to attach to the I/O operation; can be {@code null}
     * @param   handler
     *          The handler for consuming the result
     *
     * @throws  AcceptPendingException
     *          If an accept operation is already in progress on this channel
     * @throws  NotYetBoundException
     *          If this channel's socket has not yet been bound
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    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 method behaves in exactly the same manner as the accept(Object, CompletionHandler<AsynchronousSocketChannel,? super Object>) 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. 
Throws:
Returns: a Future object representing the pending result
/**
     * Accepts a connection.
     *
     * <p> 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 {@link #accept(Object, CompletionHandler)} method
     * except that instead of specifying a completion handler, this method
     * returns a {@code Future} representing the pending result. The {@code
     * Future}'s {@link Future#get() get} method returns the {@link
     * AsynchronousSocketChannel} to the new connection on successful completion.
     *
     * @return  a {@code Future} object representing the pending result
     *
     * @throws  AcceptPendingException
     *          If an accept operation is already in progress on this channel
     * @throws  NotYetBoundException
     *          If this channel's socket has not yet been bound
     */
    public abstract Future<AsynchronousSocketChannel> accept();

    
{@inheritDoc}

 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. 
Throws:
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
/**
     * {@inheritDoc}
     * <p>
     * If there is a security manager set, its {@code checkConnect} method is
     * called with the local address and {@code -1} as its arguments to see
     * if the operation is allowed. If the operation is not allowed,
     * a {@code SocketAddress} representing the
     * {@link java.net.InetAddress#getLoopbackAddress loopback} address and the
     * local port of the channel's socket is returned.
     *
     * @return  The {@code SocketAddress} that the socket is bound to, or the
     *          {@code SocketAddress} representing the loopback address if
     *          denied by the security manager, or {@code null} if the
     *          channel's socket is not bound
     *
     * @throws  ClosedChannelException     {@inheritDoc}
     * @throws  IOException                {@inheritDoc}
     */
    @Override
    public abstract SocketAddress getLocalAddress() throws IOException;
}