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	/*
	* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.nio.channels;

	import java.io.IOException;
	import java.net.ServerSocket;
	import java.net.SocketOption;
	import java.net.SocketAddress;
	import java.nio.channels.spi.AbstractSelectableChannel;
	import java.nio.channels.spi.SelectorProvider;

	/**
	* A selectable channel for stream-oriented listening sockets.
	*
	* <p> A server-socket channel is created by invoking the {@link #open() open}
	* method of this class. It is not possible to create a channel for an arbitrary,
	* pre-existing {@link ServerSocket}. A newly-created server-socket channel is
	* open but not yet bound. An attempt to invoke the {@link #accept() accept}
	* method of an unbound server-socket channel will cause a {@link NotYetBoundException}
	* to be thrown. A server-socket channel can be bound by invoking one of the
	* {@link #bind(java.net.SocketAddress,int) bind} methods defined by this class.
	*
	* <p> Socket options are configured using the {@link #setOption(SocketOption,Object)
	* setOption} method. Server-socket channels 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> Server-socket channels are safe for use by multiple concurrent threads.
	* </p>
	*
	* @author Mark Reinhold
	* @author JSR-51 Expert Group
	* @since 1.4
	*/

	public abstract class ServerSocketChannel
	extends AbstractSelectableChannel
	implements NetworkChannel
	{

	/**
	* Initializes a new instance of this class.
	*
	* @param provider
	* The provider that created this channel
	*/
	protected ServerSocketChannel(SelectorProvider provider) {
	super(provider);
	}

	/**
	* Opens a server-socket channel.
	*
	* <p> The new channel is created by invoking the {@link
	* java.nio.channels.spi.SelectorProvider#openServerSocketChannel
	* openServerSocketChannel} method of the system-wide default {@link
	* java.nio.channels.spi.SelectorProvider} object.
	*
	* <p> The new channel's socket is initially unbound; it must be bound to a
	* specific address via one of its socket's {@link
	* java.net.ServerSocket#bind(SocketAddress) bind} methods before
	* connections can be accepted. </p>
	*
	* @return A new socket channel
	*
	* @throws IOException
	* If an I/O error occurs
	*/
	public static ServerSocketChannel open() throws IOException {
	return SelectorProvider.provider().openServerSocketChannel();
	}

	/**
	* Returns an operation set identifying this channel's supported
	* operations.
	*
	* <p> Server-socket channels only support the accepting of new
	* connections, so this method returns {@link SelectionKey#OP_ACCEPT}.
	* </p>
	*
	* @return The valid-operation set
	*/
	public final int validOps() {
	return SelectionKey.OP_ACCEPT;
	}


	// -- ServerSocket-specific operations --

	/**
	* 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 ClosedChannelException {@inheritDoc}
	* @throws IOException {@inheritDoc}
	* @throws SecurityException
	* If a security manager has been installed and its {@link
	* SecurityManager#checkListen checkListen} method denies the
	* operation
	*
	* @since 1.7
	*/
	public final ServerSocketChannel 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 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 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 ClosedChannelException
	* If this channel is closed
	* @throws IOException
	* If some other I/O error occurs
	* @throws SecurityException
	* If a security manager has been installed and its {@link
	* SecurityManager#checkListen checkListen} method denies the
	* operation
	*
	* @since 1.7
	*/
	public abstract ServerSocketChannel bind(SocketAddress local, int backlog)
	throws IOException;

	/**
	* @throws UnsupportedOperationException {@inheritDoc}
	* @throws IllegalArgumentException {@inheritDoc}
	* @throws ClosedChannelException {@inheritDoc}
	* @throws IOException {@inheritDoc}
	*
	* @since 1.7
	*/
	public abstract <T> ServerSocketChannel setOption(SocketOption<T> name, T value)
	throws IOException;

	/**
	* Retrieves a server socket associated with this channel.
	*
	* <p> The returned object will not declare any public methods that are not
	* declared in the {@link java.net.ServerSocket} class. </p>
	*
	* @return A server socket associated with this channel
	*/
	public abstract ServerSocket socket();

	/**
	* Accepts a connection made to this channel's socket.
	*
	* <p> If this channel is in non-blocking mode then this method will
	* immediately return {@code null} if there are no pending connections.
	* Otherwise it will block indefinitely until a new connection is available
	* or an I/O error occurs.
	*
	* <p> The socket channel returned by this method, if any, will be in
	* blocking mode regardless of the blocking mode of this channel.
	*
	* <p> This method performs exactly the same security checks as the {@link
	* java.net.ServerSocket#accept accept} method of the {@link
	* java.net.ServerSocket} class. That is, if a security manager has been
	* installed then for each new connection this method verifies that the
	* address and port number of the connection's remote endpoint are
	* permitted by the security manager's {@link
	* java.lang.SecurityManager#checkAccept checkAccept} method. </p>
	*
	* @return The socket channel for the new connection,
	* or {@code null} if this channel is in non-blocking mode
	* and no connection is available to be accepted
	*
	* @throws ClosedChannelException
	* If this channel is closed
	*
	* @throws AsynchronousCloseException
	* If another thread closes this channel
	* while the accept operation is in progress
	*
	* @throws ClosedByInterruptException
	* If another thread interrupts the current thread
	* while the accept operation is in progress, thereby
	* closing the channel and setting the current thread's
	* interrupt status
	*
	* @throws NotYetBoundException
	* If this channel's socket has not yet been bound
	*
	* @throws SecurityException
	* If a security manager has been installed
	* and it does not permit access to the remote endpoint
	* of the new connection
	*
	* @throws IOException
	* If some other I/O error occurs
	*/
	public abstract SocketChannel accept() throws IOException;

	/**
	* {@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;

	}

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