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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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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,
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package java.nio.channels;
import java.io.IOException;
import java.net.ProtocolFamily;
import java.net.StandardProtocolFamily;
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 one of the open methods 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>Two kinds of server-socket channel are supported: <i>IP</i> (Internet Protocol)
* and <i>Unix Domain</i> depending on which open method is used to create them and which subtype of
* {@link SocketAddress} that they support for local and remote addresses.
* <i>IP</i> channels are created using {@link #open()}. They use {@link
* InetSocketAddress} addresses and support both IPv4 and IPv6 TCP/IP.
* <i>Unix Domain</i> channels are created using {@link #open(ProtocolFamily)}
* with the family parameter set to {@link StandardProtocolFamily#UNIX}.
* They use {@link UnixDomainSocketAddress}es and also
* do not support the {@link #socket()} method. Note, it is also possible to
* create channels that support either IPv4 or IPv6 only through the
* {@link #open(ProtocolFamily)} method.
*
* <p> Socket options are configured using the {@link #setOption(SocketOption,Object)
* setOption} method. <i>IP</i> 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>
*
* <p><i>Unix Domain</i> server-socket channels support a subset of the options listed above.
*
* @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 an <i>IP</i> 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 a {@link ServerSocketChannel} of the given protocol family.
* Where family is equal to {@link StandardProtocolFamily#INET} or {@link
* StandardProtocolFamily#INET6} the returned channel must be bound to an
* {@link InetSocketAddress}. If family is {@link StandardProtocolFamily#UNIX}
* the returned channel must be bound to a {@link UnixDomainSocketAddress}.
*
* @param family the protocol family
*
* @return a ServerSocketChannel
*
* @throws IOException if an I/O error occurs
* @throws UnsupportedAddressTypeException if the protocol family is not supported
* @since 14
*/
public static ServerSocketChannel open(ProtocolFamily family) throws IOException {
return SelectorProvider.provider().openServerSocketChannel(family);
}
/**
* 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 for <i>IP</i> channels. Or with <i>Unix Domain</i>
* channels, if the security manager denies "read" or "write"
* {@link java.io.FilePermission} for the local path.
*
* @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.
*
* <p> Note, for <i>Unix Domain</i> channels, a file is created in the file-system
* with the same path name as this channel's bound {@link UnixDomainSocketAddress}.
* This file persists after the channel is closed, and must be removed before
* another channel can bind to the same name.
*
* @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 for <i>IP</i> channels; or in the case of <i>Unix Domain</i>
* channels, if the security manager denies "read" or "write"
* {@link java.io.FilePermission} for the local path.
*
* @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 if it is an <i>IP</i>
* channel. The operation is not supported for <i>Unix Domain</i> channels.
*
* <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
*
* @throws UnsupportedOperationException if this is a Unix Domain 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> For <i>IP</i> channels, 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>
*
* <p> For <i>Unix Domain</i> channels, this method performs a security
* manager {@link SecurityManager#checkPermission(Permission)} using
* a {@link java.io.FilePermission} constructed with the path from the
* remote address and "read,write" as the actions.
*
* @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}
* Where the channel is bound to a <i>Unix Domain</i> address, the return
* value from this method is of type {@link UnixDomainSocketAddress}.
* <p>
* If there is a security manager set and this is an <i>IP</i> channel,
* {@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.
* <p>
* If there is a security manager set and this is a <i>Unix Domain</i> channel,
* then {@link SecurityManager#checkPermission(Permission)} is called using
* a {@link java.io.FilePermission} constructed with the path from the
* local address and "read" as the action. If this check fails
* then an unnamed {@link UnixDomainSocketAddress} (with empty pathname)
* is returned.
*
* @return The {@code SocketAddress} that the socket is bound to, or the
* {@code SocketAddress} representing the loopback address or empty
* pathname 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;
}