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* published by the Free Software Foundation. Oracle designates this
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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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.
*
* <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 <tt>accept</tt> 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 border summary="Socket options">
* <tr>
* <th>Option Name</th>
* <th>Description</th>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} </td>
* <td> The size of the socket receive buffer </td>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} </td>
* <td> Re-use address </td>
* </tr>
* </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<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) {
* ...
* }
* });
* </pre>
*
* @since 1.7
*/
public abstract class AsynchronousServerSocketChannel
implements AsynchronousChannel, NetworkChannel
{
private final AsynchronousChannelProvider provider;
/**
* 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.
*
* @return The provider that created this channel
*/
public final AsynchronousChannelProvider provider() {
return provider;
}
/**
* 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 <tt>null</tt> 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 <tt>null</tt> 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.
*
* <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.
*
* <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 <tt>null</tt> 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.
*
* <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 IllegalArgumentException {@inheritDoc}
* @throws ClosedChannelException {@inheritDoc}
* @throws IOException {@inheritDoc}
*/
public abstract <T> AsynchronousServerSocketChannel setOption(SocketOption<T> name, T value)
throws IOException;
/**
* 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.
*
* <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
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