Added in API level 1

ServerSocketChannel

abstract class ServerSocketChannel : AbstractSelectableChannel, NetworkChannel

kotlin.Any
↳	java.nio.channels.spi.AbstractInterruptibleChannel
	↳	java.nio.channels.SelectableChannel
		↳	java.nio.channels.spi.AbstractSelectableChannel
			↳	java.nio.channels.ServerSocketChannel

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.

Summary

Protected constructors
ServerSocketChannel(provider: SelectorProvider!) Initializes a new instance of this class.

Public methods
abstract SocketChannel!	accept() Accepts a connection made to this channel's socket.
ServerSocketChannel!	bind(local: SocketAddress!) Binds the channel's socket to a local address and configures the socket to listen for connections.
abstract ServerSocketChannel!	bind(local: SocketAddress!, backlog: Int) Binds the channel's socket to a local address and configures the socket to listen for connections.
abstract SocketAddress!	getLocalAddress() Returns the socket address that this channel's socket is bound to.
open static ServerSocketChannel!	open() Opens a server-socket channel.
abstract ServerSocketChannel!	setOption(name: SocketOption<T>!, value: T)
abstract ServerSocket!	socket() Retrieves a server socket associated with this channel.
Int	validOps() Returns an operation set identifying this channel's supported operations.

Inherited functions
From class AbstractInterruptibleChannel Unit begin() Marks the beginning of an I/O operation that might block indefinitely. This method should be invoked in tandem with the end method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel. Unit close() Closes this channel. If the channel has already been closed then this method returns immediately. Otherwise it marks the channel as closed and then invokes the implCloseChannel method in order to complete the close operation. Unit end(completed: Boolean) Marks the end of an I/O operation that might block indefinitely. This method should be invoked in tandem with the begin method, using a try ... finally block as shown above, in order to implement asynchronous closing and interruption for this channel. Unit implCloseChannel() Closes this channel. This method is invoked by the #close method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once. An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally. Boolean isOpen()
From class AbstractSelectableChannel Any! blockingLock() SelectableChannel! configureBlocking(block: Boolean) Adjusts this channel's blocking mode. If the given blocking mode is different from the current blocking mode then this method invokes the implConfigureBlocking method, while holding the appropriate locks, in order to change the mode. Unit implCloseChannel() Closes this channel. This method, which is specified in the AbstractInterruptibleChannel class and is invoked by the java.nio.channels.Channel#close method, in turn invokes the implCloseSelectableChannel method in order to perform the actual work of closing this channel. It then cancels all of this channel's keys. Unit implCloseSelectableChannel() Closes this selectable channel. This method is invoked by the java.nio.channels.Channel#close method in order to perform the actual work of closing the channel. This method is only invoked if the channel has not yet been closed, and it is never invoked more than once. An implementation of this method must arrange for any other thread that is blocked in an I/O operation upon this channel to return immediately, either by throwing an exception or by returning normally. Unit implConfigureBlocking(block: Boolean) Adjusts this channel's blocking mode. This method is invoked by the configureBlocking method in order to perform the actual work of changing the blocking mode. This method is only invoked if the new mode is different from the current mode. Boolean isBlocking() Boolean isRegistered() SelectionKey! keyFor(sel: Selector!) SelectorProvider! provider() Returns the provider that created this channel. SelectionKey! register(sel: Selector!, ops: Int, att: Any!) Registers this channel with the given selector, returning a selection key. This method first verifies that this channel is open and that the given initial interest set is valid. If this channel is already registered with the given selector then the selection key representing that registration is returned after setting its interest set to the given value. Otherwise this channel has not yet been registered with the given selector, so the register method of the selector is invoked while holding the appropriate locks. The resulting key is added to this channel's key set before being returned.
From class Channel Unit close() Closes this channel. After a channel is closed, any further attempt to invoke I/O operations upon it will cause a ClosedChannelException to be thrown. If this channel is already closed then invoking this method has no effect. This method may be invoked at any time. If some other thread has already invoked it, however, then another invocation will block until the first invocation is complete, after which it will return without effect. Boolean isOpen() Tells whether or not this channel is open.
From class NetworkChannel T getOption(name: SocketOption<T>!) Returns the value of a socket option. MutableSet<SocketOption<*>!>! supportedOptions() Returns a set of the socket options supported by this channel. This method will continue to return the set of options even after the channel has been closed.
From class SelectableChannel SelectionKey! register(sel: Selector!, ops: Int) Registers this channel with the given selector, returning a selection key. An invocation of this convenience method of the form sc.register(sel, ops) behaves in exactly the same way as the invocation sc. register(sel, ops, null) Int validOps() Returns an operation set identifying this channel's supported operations. The bits that are set in this integer value denote exactly the operations that are valid for this channel. This method always returns the same value for a given concrete channel class.

Protected constructors

ServerSocketChannel

Added in API level 1

protected ServerSocketChannel(provider: SelectorProvider!)

Initializes a new instance of this class.

Parameters
provider	SelectorProvider!: The provider that created this channel

Public methods

accept

Added in API level 1

abstract fun accept(): SocketChannel!

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 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.

Return
SocketChannel!	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

Exceptions
java.nio.channels.ClosedChannelException	If this channel is closed
java.nio.channels.AsynchronousCloseException	If another thread closes this channel while the accept operation is in progress
java.nio.channels.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
java.nio.channels.NotYetBoundException	If this channel's socket has not yet been bound
java.lang.SecurityException	If a security manager has been installed and it does not permit access to the remote endpoint of the new connection
java.io.IOException	If some other I/O error occurs

bind

Added in API level 24

fun bind(local: SocketAddress!): ServerSocketChannel!

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);
  

Parameters
local	SocketAddress!: The local address to bind the socket, or null to bind to an automatically assigned socket address

Return
ServerSocketChannel!	This channel

Exceptions
java.nio.channels.AlreadyBoundException	If the socket is already bound
java.nio.channels.UnsupportedAddressTypeException	If the type of the given address is not supported
java.nio.channels.ClosedChannelException	If the channel is closed
java.io.IOException	If some other I/O error occurs
java.lang.SecurityException	If a security manager has been installed and its checkListen method denies the operation

bind

Added in API level 24

abstract fun bind(
    local: SocketAddress!, 
    backlog: Int
): ServerSocketChannel!

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.

Parameters
local	SocketAddress!: The address to bind the socket, or null to bind to an automatically assigned socket address
backlog	Int: The maximum number of pending connections

Return
ServerSocketChannel!	This channel

Exceptions
java.nio.channels.AlreadyBoundException	If the socket is already bound
java.nio.channels.UnsupportedAddressTypeException	If the type of the given address is not supported
java.nio.channels.ClosedChannelException	If this channel is closed
java.io.IOException	If some other I/O error occurs
java.lang.SecurityException	If a security manager has been installed and its checkListen method denies the operation

getLocalAddress

Added in API level 24

abstract fun getLocalAddress(): SocketAddress!

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 .

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.

Return
SocketAddress!	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

Exceptions
java.nio.channels.ClosedChannelException	If the channel is closed
java.io.IOException	If an I/O error occurs

open

Added in API level 1

open static fun open(): ServerSocketChannel!

Opens a server-socket channel.

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

Return
ServerSocketChannel!	A new socket channel

Exceptions
java.io.IOException	If an I/O error occurs

setOption

Added in API level 24

abstract fun <T : Any!> setOption(
    name: SocketOption<T>!, 
    value: T
): ServerSocketChannel!

Parameters
<T>	The type of the socket option value
name	SocketOption<T>!: The socket option
value	T: The value of the socket option. A value of null may be a valid value for some socket options.

Return
ServerSocketChannel!	This channel

Exceptions
java.lang.UnsupportedOperationException	If the socket option is not supported by this channel
java.lang.IllegalArgumentException	If the value is not a valid value for this socket option
java.nio.channels.ClosedChannelException	If this channel is closed
java.io.IOException	If an I/O error occurs

socket

Added in API level 1

abstract fun socket(): ServerSocket!

Retrieves a server socket associated with this channel.

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

Return
ServerSocket!	A server socket associated with this channel

validOps

Added in API level 1

fun validOps(): Int

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.

Return
Int	The valid-operation set