Module java.base

Class ServerSocketChannel

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Channel, InterruptibleChannel, NetworkChannel

    public abstract class ServerSocketChannel
    extends AbstractSelectableChannel
    implements NetworkChannel
    A selectable channel for stream-oriented listening sockets.

    A server-socket channel is created by invoking the open method of this class. It is not possible to create a channel for an arbitrary, pre-existing ServerSocket. A newly-created server-socket channel is open but not yet bound. An attempt to invoke the accept method of an unbound server-socket channel will cause a NotYetBoundException to be thrown. A server-socket channel can be bound by invoking one of the bind methods defined by this class.

    Socket options are configured using the setOption method. Server-socket channels 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.

    Server-socket channels are safe for use by multiple concurrent threads.

    • Constructor Detail

      • ServerSocketChannel

        protected ServerSocketChannel​(SelectorProvider provider)
        Initializes a new instance of this class.
        provider - The provider that created this channel
    • Method Detail

      • open

        public static ServerSocketChannel open()
                                        throws IOException
        Opens a server-socket channel.

        The new channel is created by invoking the openServerSocketChannel method of the system-wide default SelectorProvider object.

        The new channel's socket is initially unbound; it must be bound to a specific address via one of its socket's bind methods before connections can be accepted.

        A new socket channel
        IOException - If an I/O error occurs
      • validOps

        public final int validOps()
        Returns an operation set identifying this channel's supported operations.

        Server-socket channels only support the accepting of new connections, so this method returns SelectionKey.OP_ACCEPT.

        Specified by:
        validOps in class SelectableChannel
        The valid-operation set
      • bind

        public abstract ServerSocketChannel bind​(SocketAddress local,
                                                 int backlog)
                                          throws IOException
        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 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.

        local - The address to bind the socket, or null to bind to an automatically assigned socket address
        backlog - The maximum number of pending connections
        This channel
        AlreadyBoundException - If the socket is already bound
        UnsupportedAddressTypeException - If the type of the given address is not supported
        ClosedChannelException - If this channel is closed
        IOException - If some other I/O error occurs
        SecurityException - If a security manager has been installed and its checkListen method denies the operation
      • socket

        public abstract ServerSocket socket()
        Retrieves a server socket associated with this channel.

        The returned object will not declare any public methods that are not declared in the ServerSocket class.

        A server socket associated with this channel
      • accept

        public abstract SocketChannel accept()
                                      throws IOException
        Accepts a connection made to this channel's socket.

        If this channel is in non-blocking mode then this method will immediately return 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.

        This method performs exactly the same security checks as the accept method of the 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 checkAccept method.

        The socket channel for the new connection, or null if this channel is in non-blocking mode and no connection is available to be accepted
        ClosedChannelException - If this channel is closed
        AsynchronousCloseException - If another thread closes this channel while the accept operation is in progress
        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
        NotYetBoundException - If this channel's socket has not yet been bound
        SecurityException - If a security manager has been installed and it does not permit access to the remote endpoint of the new connection
        IOException - If some other I/O error occurs
      • getLocalAddress

        public abstract SocketAddress getLocalAddress()
                                               throws IOException
        Returns the socket address that this channel's socket is bound to.

        Where the channel is bound to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress.

        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.

        Specified by:
        getLocalAddress in interface NetworkChannel
        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
        ClosedChannelException - If the channel is closed
        IOException - If an I/O error occurs