A server-socket channel is created by invoking one of the {@code open} * methods of this class. The no-arg {@link #open() open} method opens a server-socket * channel for an Internet protocol socket. The {@link #open(ProtocolFamily)} * method is used to open a server-socket channel for a socket of a specified * protocol family. It is not possible to create a channel for an arbitrary, * pre-existing socket. 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. * *
Socket options are configured using the {@link #setOption(SocketOption,Object) * setOption} method. Server-socket channels for Internet protocol sockets * support the following options: *
** ** * *
** * * *Option Name *Description ** *{@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} *The size of the socket receive buffer ** * *{@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} *Re-use address *
Server-socket channels for Unix domain sockets support: *
** ** * *
** * * *Option Name *Description ** * *{@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} *The size of the socket receive buffer *
Additional (implementation specific) options may also be supported. * *
Server-socket channels are safe for use by multiple concurrent threads. *
* * @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 for an Internet protocol socket. * *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. * *
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.
* * @return A new socket channel * * @throws IOException * If an I/O error occurs * * @see * java.net.preferIPv4Stack system property */ public static ServerSocketChannel open() throws IOException { return SelectorProvider.provider().openServerSocketChannel(); } /** * Opens a server-socket channel. The {@code family} parameter specifies the * {@link ProtocolFamily protocol family} of the channel's socket. * *The new channel is created by invoking the {@link * java.nio.channels.spi.SelectorProvider#openServerSocketChannel(ProtocolFamily) * openServerSocketChannel(ProtocolFamily)} method of the system-wide default {@link * java.nio.channels.spi.SelectorProvider} object.
* * @param family * The protocol family * * @return A new socket channel * * @throws UnsupportedOperationException * If the specified protocol family is not supported. For example, * suppose the parameter is specified as {@link * java.net.StandardProtocolFamily#INET6 StandardProtocolFamily.INET6} * but IPv6 is not enabled on the platform. * @throws IOException * If an I/O error occurs * * @see * java.net.preferIPv4Stack system property * * @since 15 */ public static ServerSocketChannel open(ProtocolFamily family) throws IOException { return SelectorProvider.provider().openServerSocketChannel(requireNonNull(family)); } /** * Returns an operation set identifying this channel's supported * operations. * *Server-socket channels only support the accepting of new * connections, so this method returns {@link SelectionKey#OP_ACCEPT}. *
* * @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. * *An invocation of this method is equivalent to the following: *
* bind(local, 0);
* This method is used to establish an association between the socket and * a local address. For Internet protocol sockets, once an association * is established then the socket remains bound until the channel is closed. * *
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.
*
* @apiNote
* Binding a server socket channel for a Unix Domain socket, creates a
* file corresponding to the file path in the {@link UnixDomainSocketAddress}.
* This file persists after the channel is closed, and must be removed before
* another socket can bind to the same name. Binding to a {@code null} address
* causes the socket to be automatically bound to some unique file
* in a system temporary location. The associated socket file also persists
* after the channel is closed. Its name can be obtained from the channel's
* local socket address.
*
* @implNote
* Each platform enforces an implementation specific, maximum length for the
* name of a Unix Domain socket. This limitation is enforced when a
* channel is bound. The maximum length is typically close to and generally
* not less than 100 bytes.
*
* @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 an Internet protocol socket address,
* or for a Unix domain socket address if it denies
* {@link NetPermission}{@code("accessUnixDomainSocket")}.
*
* @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 The returned object will not declare any public methods that are not
* declared in the {@link java.net.ServerSocket} class. 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.
*
* The socket channel returned by this method, if any, will be in
* blocking mode regardless of the blocking mode of this channel.
*
* If bound to an Internet protocol socket address, 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. If bound to a Unix Domain socket address, this method checks
* {@link NetPermission}{@code ("accessUnixDomainSocket")}.
*
* @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}
*
* 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.
*
* Where the channel is bound to a Unix Domain socket address, the socket
* address is a {@link UnixDomainSocketAddress}. If there is a security manager
* set, its {@link SecurityManager#checkPermission(java.security.Permission)
* checkPermission} method is called with {@link NetPermission}{@code
* ("accessUnixDomainSocket")}. If the operation is not allowed an unnamed
* {@link UnixDomainSocketAddress} is returned.
*
* @return The {@code SocketAddress} that the socket is bound to, or the
* {@code SocketAddress} representing the loopback address or empty
* path 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;
}