Class ServerSocketChannel

java.nio.channels.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 one of the open methods of this class. The no-arg open method opens a server-socket channel for an Internet protocol socket. The 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 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 for Internet protocol sockets support the following options:

Socket options

Option Name Description

SO_RCVBUF The size of the socket receive buffer

SO_REUSEADDR Re-use address

Socket options
Option Name	Description
`SO_RCVBUF`	The size of the socket receive buffer
`SO_REUSEADDR`	Re-use address

Server-socket channels for Unix domain sockets support:

Socket options

Option Name Description

SO_RCVBUF The size of the socket receive buffer

Socket options
Option Name	Description
`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.

Since:: 1.4

Constructor Summary

ServerSocketChannel(SelectorProvider provider)

Modifier	Constructor	Description
`protected`	Initializes a new instance of this class.

Method Summary

Modifier and Type	Method	Description
`abstract SocketChannel`	`accept()`	Accepts a connection made to this channel's socket.
`final ServerSocketChannel`	`bind(SocketAddress local)`	Binds the channel's socket to a local address and configures the socket to listen for connections.
`abstract ServerSocketChannel`	`bind(SocketAddress local, int backlog)`	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.
`static ServerSocketChannel`	`open()`	Opens a server-socket channel for an Internet protocol socket.
`static ServerSocketChannel`	`open(ProtocolFamily family)`	Opens a server-socket channel.
`abstract <T> ServerSocketChannel`	`setOption(SocketOption<T> name, T value)`	Sets the value of a socket option.
`abstract ServerSocket`	`socket()`	Retrieves a server socket associated with this channel.
`final int`	`validOps()`	Returns an operation set identifying this channel's supported operations.

Methods declared in class AbstractSelectableChannel

blockingLock, configureBlocking, implCloseChannel, implCloseSelectableChannel, implConfigureBlocking, isBlocking, isRegistered, keyFor, provider, register

Modifier and Type	Method	Description
`final Object`	`blockingLock()`	Retrieves the object upon which the `configureBlocking` and `register` methods synchronize.
`final SelectableChannel`	`configureBlocking(boolean block)`	Adjusts this channel's blocking mode.
`protected final void`	`implCloseChannel()`	Closes this channel.
`protected abstract void`	`implCloseSelectableChannel()`	Closes this selectable channel.
`protected abstract void`	`implConfigureBlocking(boolean block)`	Adjusts this channel's blocking mode.
`final boolean`	`isBlocking()`	Tells whether or not every I/O operation on this channel will block until it completes.
`final boolean`	`isRegistered()`	Tells whether or not this channel is currently registered with any selectors.
`final SelectionKey`	`keyFor(Selector sel)`	Retrieves the key representing the channel's registration with the given selector.
`final SelectorProvider`	`provider()`	Returns the provider that created this channel.
`final SelectionKey`	`register(Selector sel, int ops, Object att)`	Registers this channel with the given selector, returning a selection key.

Methods declared in class SelectableChannel

register

Modifier and Type	Method	Description
`final SelectionKey`	`register(Selector sel, int ops)`	Registers this channel with the given selector, returning a selection key.

Methods declared in class AbstractInterruptibleChannel

begin, close, end, isOpen

Modifier and Type	Method	Description
`protected final void`	`begin()`	Marks the beginning of an I/O operation that might block indefinitely.
`final void`	`close()`	Closes this channel.
`protected final void`	`end(boolean completed)`	Marks the end of an I/O operation that might block indefinitely.
`final boolean`	`isOpen()`	Tells whether or not this channel is open.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Modifier and Type	Method	Description
`protected Object`	`clone()`	Creates and returns a copy of this object.
`boolean`	`equals(Object obj)`	Indicates whether some other object is "equal to" this one.
`protected void`	`finalize()`	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
`final Class<?>`	`getClass()`	Returns the runtime class of this `Object`.
`int`	`hashCode()`	Returns a hash code value for this object.
`final void`	`notify()`	Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()`	Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()`	Returns a string representation of the object.
`final void`	`wait()`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
`final void`	`wait(long timeoutMillis)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis, int nanos)`	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Methods declared in interface NetworkChannel

getOption, supportedOptions

Modifier and Type	Method	Description
`<T> T`	`getOption(SocketOption<T> name)`	Returns the value of a socket option.
`Set<SocketOption<?>>`	`supportedOptions()`	Returns a set of the socket options supported by this channel.

Constructor Details

ServerSocketChannel

protected ServerSocketChannel(SelectorProvider provider)

Initializes a new instance of this class.

Parameters:: provider - The provider that created this channel

Method Details

open

public static ServerSocketChannel open() throws IOException

Opens a server-socket channel for an Internet protocol socket.

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.

Returns:

A new socket channel

Throws:

IOException - If an I/O error occurs

See Also:

open

public static ServerSocketChannel open(ProtocolFamily family) throws IOException

Opens a server-socket channel. The family parameter specifies the protocol family of the channel's socket.

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

Parameters:

family - The protocol family

Returns:

A new socket channel

Throws:

UnsupportedOperationException - If the specified protocol family is not supported. For example, suppose the parameter is specified as StandardProtocolFamily.INET6 but IPv6 is not enabled on the platform.

IOException - If an I/O error occurs

Since:

See Also:

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
Returns:: The valid-operation set

bind

public final ServerSocketChannel bind(SocketAddress local) throws IOException

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);

Specified by:

bind in interface NetworkChannel

Parameters:

local - The local address to bind the socket, or null to bind to an automatically assigned socket address

Returns:

This channel

Throws:

AlreadyBoundException - If the socket is already bound

UnsupportedAddressTypeException - If the type of the given address is not supported

ClosedChannelException - If the channel is closed

IOException - If some other I/O error occurs

Since:

1.7

See Also:

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. For Internet protocol sockets, 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 altogether. If the backlog parameter has the value 0, or a negative value, then an implementation specific default is used.

API Note:: Binding a server socket channel for a Unix Domain socket, creates a file corresponding to the file path in the 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 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.
Implementation Note:: 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. This limitation also applies to automatically bound server socket channels. See the Unix domain networking properties that can be used to select the temporary directory where these sockets are created.
Parameters:: local - The address to bind the socket, or null to bind to an automatically assigned socket address; backlog - The maximum number of pending connections
Returns:: This channel
Throws:: 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
Since:: 1.7

setOption

public abstract <T> ServerSocketChannel setOption(SocketOption<T> name, T value) throws IOException

Description copied from interface: NetworkChannel

Sets the value of a socket option.

Specified by:

setOption in interface NetworkChannel

Type Parameters:

T - The type of the socket option value

Parameters:

name - The socket option

value - The value of the socket option. A value of null may be a valid value for some socket options.

Returns:

This channel

Throws:

UnsupportedOperationException - If the socket option is not supported by this channel

IllegalArgumentException - If the value is not a valid value for this socket option

ClosedChannelException - If this channel is closed

IOException - If an I/O error occurs

Since:

1.7

See Also:

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.

Returns:: A server socket associated with this channel
Throws:: UnsupportedOperationException - If the channel's socket is not an Internet protocol socket

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.

Returns:: 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
Throws:: 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 interrupted status; NotYetBoundException - If this channel's socket has not yet been bound; 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.

Where the channel is bound to a Unix Domain socket address, the socket address is a UnixDomainSocketAddress.

Specified by:: getLocalAddress in interface NetworkChannel
Returns:: The SocketAddress that the socket is bound to or null if the channel's socket is not bound
Throws:: ClosedChannelException - If the channel is closed; IOException - If an I/O error occurs

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