AsynchronousSocketChannel

abstract class AsynchronousSocketChannel : AsynchronousByteChannel, NetworkChannel
kotlin.Any
   ↳ java.nio.channels.AsynchronousSocketChannel

An asynchronous channel for stream-oriented connecting sockets.

Asynchronous socket channels are created in one of two ways. A newly-created AsynchronousSocketChannel is created by invoking one of the methods defined by this class. A newly-created channel is open but not yet connected. A connected AsynchronousSocketChannel is created when a connection is made to the socket of an AsynchronousServerSocketChannel. It is not possible to create an asynchronous socket channel for an arbitrary, pre-existing socket.

A newly-created channel is connected by invoking its connect method; once connected, a channel remains connected until it is closed. Whether or not a socket channel is connected may be determined by invoking its method. An attempt to invoke an I/O operation upon an unconnected channel will cause a NotYetConnectedException to be thrown.

Channels of this type are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one read operation and one write operation can be outstanding at any time. If a thread initiates a read operation before a previous read operation has completed then a ReadPendingException will be thrown. Similarly, an attempt to initiate a write operation before a previous write has completed will throw a WritePendingException.

Socket options are configured using the setOption method. Asynchronous socket channels support the following options:

Option Name Description SO_SNDBUF The size of the socket send buffer SO_RCVBUF The size of the socket receive buffer SO_KEEPALIVE Keep connection alive SO_REUSEADDR Re-use address TCP_NODELAY Disable the Nagle algorithm Additional (implementation specific) options may also be supported. Timeouts

The read and write methods defined by this class allow a timeout to be specified when initiating a read or write operation. If the timeout elapses before an operation completes then the operation completes with the exception . A timeout may leave the channel, or the underlying connection, in an inconsistent state. Where the implementation cannot guarantee that bytes have not been read from the channel then it puts the channel into an implementation specific error state. A subsequent attempt to initiate a read operation causes an unspecified runtime exception to be thrown. Similarly if a write operation times out and the implementation cannot guarantee bytes have not been written to the channel then further attempts to write to the channel cause an unspecified runtime exception to be thrown. When a timeout elapses then the state of the ByteBuffer, or the sequence of buffers, for the I/O operation is not defined. Buffers should be discarded or at least care must be taken to ensure that the buffers are not accessed while the channel remains open. All methods that accept timeout parameters treat values less than or equal to zero to mean that the I/O operation does not timeout.
Requires API level 26 (Android 8.0, Oreo)

Summary

Protected constructors

Initializes a new instance of this class.

Public methods
abstract SocketAddress!

Returns the socket address that this channel's socket is bound to.

abstract Unit
write(src: ByteBuffer!, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Int!, in A>!)

Writes a sequence of bytes to this channel from the given buffer.

Unit
write(src: ByteBuffer!, attachment: A, handler: CompletionHandler<Int!, in A>!)


Requires API level 26 (Android 8.0, Oreo)

abstract Future<Int!>!


Requires API level 26 (Android 8.0, Oreo)

abstract Unit
write(srcs: Array<ByteBuffer!>!, offset: Int, length: Int, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Long!, in A>!)

Writes a sequence of bytes to this channel from a subsequence of the given buffers.

abstract AsynchronousSocketChannel!
setOption(name: SocketOption<T>!, value: T)


Requires API level 26 (Android 8.0, Oreo)

abstract Unit
connect(remote: SocketAddress!, attachment: A, handler: CompletionHandler<Void!, in A>!)

Connects this channel.

abstract Future<Void!>!

Connects this channel.

AsynchronousChannelProvider!

Returns the provider that created this channel.

abstract AsynchronousSocketChannel!


Requires API level 26 (Android 8.0, Oreo)

abstract AsynchronousSocketChannel!

Shutdown the connection for reading without closing the channel.

abstract AsynchronousSocketChannel!

Shutdown the connection for writing without closing the channel.

abstract Unit
read(dst: ByteBuffer!, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Int!, in A>!)

Reads a sequence of bytes from this channel into the given buffer.

Unit
read(dst: ByteBuffer!, attachment: A, handler: CompletionHandler<Int!, in A>!)


Requires API level 26 (Android 8.0, Oreo)

abstract Future<Int!>!


Requires API level 26 (Android 8.0, Oreo)

abstract Unit
read(dsts: Array<ByteBuffer!>!, offset: Int, length: Int, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Long!, in A>!)

Reads a sequence of bytes from this channel into a subsequence of the given buffers.

abstract SocketAddress!

Returns the remote address to which this channel's socket is connected.

open static AsynchronousSocketChannel!

Opens an asynchronous socket channel.

open static AsynchronousSocketChannel!

Opens an asynchronous socket channel.

Inherited functions

Protected constructors

<init>

protected AsynchronousSocketChannel(provider: AsynchronousChannelProvider!)

Initializes a new instance of this class.

Parameters
provider AsynchronousChannelProvider!: The provider that created this channel

Public methods

getLocalAddress

added in API level 26
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 .
Requires API level 24 (Android 7.0, Nougat)

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.
Requires API level 26 (Android 8.0, Oreo)

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
ClosedChannelException If the channel is closed
IOException If an I/O error occurs

write

added in API level 26
abstract fun <A : Any!> write(src: ByteBuffer!, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Int!, in A>!): Unit

Writes a sequence of bytes to this channel from the given buffer.

This method initiates an asynchronous write operation to write a sequence of bytes to this channel from the given buffer. The handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written.

If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception . Where a timeout occurs, and the implementation cannot guarantee that bytes have not been written, or will not be written to the channel from the given buffer, then further attempts to write to the channel will cause an unspecific runtime exception to be thrown.

Otherwise this method works in the same manner as the method.
Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> ByteBuffer!: The type of the attachment
src ByteBuffer!: The buffer from which bytes are to be retrieved
timeout ByteBuffer!: The maximum time for the I/O operation to complete
unit ByteBuffer!: The time unit of the timeout argument
attachment ByteBuffer!: The object to attach to the I/O operation; can be null
handler ByteBuffer!: The handler for consuming the result
Exceptions
WritePendingException If a write operation is already in progress on this channel
NotYetConnectedException If this channel is not yet connected
ShutdownChannelGroupException If the channel group has terminated

write

added in API level 26
fun <A : Any!> write(src: ByteBuffer!, attachment: A, handler: CompletionHandler<Int!, in A>!): Unit


Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> ByteBuffer!: The type of the attachment
src ByteBuffer!: The buffer from which bytes are to be retrieved
attachment ByteBuffer!: The object to attach to the I/O operation; can be null
handler ByteBuffer!: The completion handler object
Exceptions
WritePendingException If the channel does not allow more than one write to be outstanding and a previous write has not completed
ShutdownChannelGroupException If the channel group has terminated
NotYetConnectedException If this channel is not yet connected

write

added in API level 26
abstract fun write(src: ByteBuffer!): Future<Int!>!


Requires API level 26 (Android 8.0, Oreo)

Parameters
src ByteBuffer!: The buffer from which bytes are to be retrieved
Return
Future<Int!>!: A Future representing the result of the operation
Exceptions
WritePendingException If the channel does not allow more than one write to be outstanding and a previous write has not completed
NotYetConnectedException If this channel is not yet connected

write

added in API level 26
abstract fun <A : Any!> write(srcs: Array<ByteBuffer!>!, offset: Int, length: Int, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Long!, in A>!): Unit

Writes a sequence of bytes to this channel from a subsequence of the given buffers. This operation, sometimes called a gathering write, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written.

This method initiates a write of up to r bytes to this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is,

 srcs[offset].remaining() + srcs[offset+1].remaining() + ... + srcs[offset+length-1].remaining()
at the moment that the write is attempted.

Suppose that a byte sequence of length n is written, where 0 < n <= r. Up to the first srcs[offset].remaining() bytes of this sequence are written from buffer srcs[offset], up to the next srcs[offset+1].remaining() bytes are written from buffer srcs[offset+1], and so forth, until the entire byte sequence is written. As many bytes as possible are written from each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system.

If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception . Where a timeout occurs, and the implementation cannot guarantee that bytes have not been written, or will not be written to the channel from the given buffers, then further attempts to write to the channel will cause an unspecific runtime exception to be thrown.
Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> Array<ByteBuffer!>!: The type of the attachment
srcs Array<ByteBuffer!>!: The buffers from which bytes are to be retrieved
offset Array<ByteBuffer!>!: The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length
length Array<ByteBuffer!>!: The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
timeout Array<ByteBuffer!>!: The maximum time for the I/O operation to complete
unit Array<ByteBuffer!>!: The time unit of the timeout argument
attachment Array<ByteBuffer!>!: The object to attach to the I/O operation; can be null
handler Array<ByteBuffer!>!: The handler for consuming the result
Exceptions
IndexOutOfBoundsException If the pre-conditions for the offset and length parameter aren't met
WritePendingException If a write operation is already in progress on this channel
NotYetConnectedException If this channel is not yet connected
ShutdownChannelGroupException If the channel group has terminated

setOption

added in API level 26
abstract fun <T : Any!> setOption(name: SocketOption<T>!, value: T): AsynchronousSocketChannel!


Requires API level 26 (Android 8.0, Oreo)

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

connect

added in API level 26
abstract fun <A : Any!> connect(remote: SocketAddress!, attachment: A, handler: CompletionHandler<Void!, in A>!): Unit

Connects this channel.

This method initiates an operation to connect this channel. The handler parameter is a completion handler that is invoked when the connection is successfully established or connection cannot be established. If the connection cannot be established then the channel is closed.

This method performs exactly the same security checks as the class. That is, if a security manager has been installed then this method verifies that its method permits connecting to the address and port number of the given remote endpoint.
Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> SocketAddress!: The type of the attachment
remote SocketAddress!: The remote address to which this channel is to be connected
attachment SocketAddress!: The object to attach to the I/O operation; can be null
handler SocketAddress!: The handler for consuming the result
Exceptions
UnresolvedAddressException If the given remote address is not fully resolved
UnsupportedAddressTypeException If the type of the given remote address is not supported
AlreadyConnectedException If this channel is already connected
ConnectionPendingException If a connection operation is already in progress on this channel
ShutdownChannelGroupException If the channel group has terminated
SecurityException If a security manager has been installed and it does not permit access to the given remote endpoint

connect

added in API level 26
abstract fun connect(remote: SocketAddress!): Future<Void!>!

Connects this channel.

This method initiates an operation to connect this channel. This method behaves in exactly the same manner as the method except that instead of specifying a completion handler, this method returns a Future representing the pending result. The Future's method returns null on successful completion.
Requires API level 26 (Android 8.0, Oreo)

Parameters
remote SocketAddress!: The remote address to which this channel is to be connected
Return
Future<Void!>!: A Future object representing the pending result
Exceptions
UnresolvedAddressException If the given remote address is not fully resolved
UnsupportedAddressTypeException If the type of the given remote address is not supported
AlreadyConnectedException If this channel is already connected
ConnectionPendingException If a connection operation is already in progress on this channel
SecurityException If a security manager has been installed and it does not permit access to the given remote endpoint

provider

added in API level 26
fun provider(): AsynchronousChannelProvider!

Returns the provider that created this channel.
Requires API level 26 (Android 8.0, Oreo)

Return
AsynchronousChannelProvider!: The provider that created this channel

bind

added in API level 26
abstract fun bind(local: SocketAddress!): AsynchronousSocketChannel!


Requires API level 26 (Android 8.0, Oreo)

Parameters
local SocketAddress!: The address to bind the socket, or null to bind the socket to an automatically assigned socket address
Return
AsynchronousSocketChannel!: This channel
Exceptions
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
SecurityException If a security manager has been installed and its checkListen method denies the operation
ConnectionPendingException If a connection operation is already in progress on this channel

shutdownInput

added in API level 26
abstract fun shutdownInput(): AsynchronousSocketChannel!

Shutdown the connection for reading without closing the channel.

Once shutdown for reading then further reads on the channel will return -1, the end-of-stream indication. If the input side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding read operation is system dependent and therefore not specified. The effect, if any, when there is data in the socket receive buffer that has not been read, or data arrives subsequently, is also system dependent.
Requires API level 26 (Android 8.0, Oreo)

Return
AsynchronousSocketChannel!: The channel
Exceptions
NotYetConnectedException If this channel is not yet connected
ClosedChannelException If this channel is closed
IOException If some other I/O error occurs

shutdownOutput

added in API level 26
abstract fun shutdownOutput(): AsynchronousSocketChannel!

Shutdown the connection for writing without closing the channel.

Once shutdown for writing then further attempts to write to the channel will throw ClosedChannelException. If the output side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding write operation is system dependent and therefore not specified.
Requires API level 26 (Android 8.0, Oreo)

Return
AsynchronousSocketChannel!: The channel
Exceptions
NotYetConnectedException If this channel is not yet connected
ClosedChannelException If this channel is closed
IOException If some other I/O error occurs

read

added in API level 26
abstract fun <A : Any!> read(dst: ByteBuffer!, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Int!, in A>!): Unit

Reads a sequence of bytes from this channel into the given buffer.

This method initiates an asynchronous read operation to read a sequence of bytes from this channel into the given buffer. The handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream.

If a timeout is specified and the timeout elapses before the operation completes then the operation completes with the exception . Where a timeout occurs, and the implementation cannot guarantee that bytes have not been read, or will not be read from the channel into the given buffer, then further attempts to read from the channel will cause an unspecific runtime exception to be thrown.

Otherwise this method works in the same manner as the method.
Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> ByteBuffer!: The type of the attachment
dst ByteBuffer!: The buffer into which bytes are to be transferred
timeout ByteBuffer!: The maximum time for the I/O operation to complete
unit ByteBuffer!: The time unit of the timeout argument
attachment ByteBuffer!: The object to attach to the I/O operation; can be null
handler ByteBuffer!: The handler for consuming the result
Exceptions
IllegalArgumentException If the buffer is read-only
ReadPendingException If a read operation is already in progress on this channel
NotYetConnectedException If this channel is not yet connected
ShutdownChannelGroupException If the channel group has terminated

read

added in API level 26
fun <A : Any!> read(dst: ByteBuffer!, attachment: A, handler: CompletionHandler<Int!, in A>!): Unit


Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> ByteBuffer!: The type of the attachment
dst ByteBuffer!: The buffer into which bytes are to be transferred
attachment ByteBuffer!: The object to attach to the I/O operation; can be null
handler ByteBuffer!: The completion handler
Exceptions
IllegalArgumentException If the buffer is read-only
ReadPendingException If the channel does not allow more than one read to be outstanding and a previous read has not completed
ShutdownChannelGroupException If the channel group has terminated
NotYetConnectedException If this channel is not yet connected

read

added in API level 26
abstract fun read(dst: ByteBuffer!): Future<Int!>!


Requires API level 26 (Android 8.0, Oreo)

Parameters
dst ByteBuffer!: The buffer into which bytes are to be transferred
Return
Future<Int!>!: A Future representing the result of the operation
Exceptions
IllegalArgumentException If the buffer is read-only
ReadPendingException If the channel does not allow more than one read to be outstanding and a previous read has not completed
NotYetConnectedException If this channel is not yet connected

read

added in API level 26
abstract fun <A : Any!> read(dsts: Array<ByteBuffer!>!, offset: Int, length: Int, timeout: Long, unit: TimeUnit!, attachment: A, handler: CompletionHandler<Long!, in A>!): Unit

Reads a sequence of bytes from this channel into a subsequence of the given buffers. This operation, sometimes called a scattering read, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream.

This method initiates a read of up to r bytes from this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is,

 dsts[offset].remaining() + dsts[offset+1].remaining() + ... + dsts[offset+length-1].remaining()
at the moment that the read is attempted.

Suppose that a byte sequence of length n is read, where 0 < n <= r. Up to the first dsts[offset].remaining() bytes of this sequence are transferred into buffer dsts[offset], up to the next dsts[offset+1].remaining() bytes are transferred into buffer dsts[offset+1], and so forth, until the entire byte sequence is transferred into the given buffers. As many bytes as possible are transferred into each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system.

If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception . Where a timeout occurs, and the implementation cannot guarantee that bytes have not been read, or will not be read from the channel into the given buffers, then further attempts to read from the channel will cause an unspecific runtime exception to be thrown.
Requires API level 26 (Android 8.0, Oreo)

Parameters
<A> Array<ByteBuffer!>!: The type of the attachment
dsts Array<ByteBuffer!>!: The buffers into which bytes are to be transferred
offset Array<ByteBuffer!>!: The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length
length Array<ByteBuffer!>!: The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset
timeout Array<ByteBuffer!>!: The maximum time for the I/O operation to complete
unit Array<ByteBuffer!>!: The time unit of the timeout argument
attachment Array<ByteBuffer!>!: The object to attach to the I/O operation; can be null
handler Array<ByteBuffer!>!: The handler for consuming the result
Exceptions
IndexOutOfBoundsException If the pre-conditions for the offset and length parameter aren't met
IllegalArgumentException If the buffer is read-only
ReadPendingException If a read operation is already in progress on this channel
NotYetConnectedException If this channel is not yet connected
ShutdownChannelGroupException If the channel group has terminated

getRemoteAddress

added in API level 26
abstract fun getRemoteAddress(): SocketAddress!

Returns the remote address to which this channel's socket is connected.

Where the channel is bound and connected to an Internet Protocol socket address then the return value from this method is of type .
Requires API level 26 (Android 8.0, Oreo)

Return
SocketAddress!: The remote address; null if the channel's socket is not connected
Exceptions
ClosedChannelException If the channel is closed
IOException If an I/O error occurs

open

added in API level 26
open static fun open(group: AsynchronousChannelGroup!): AsynchronousSocketChannel!

Opens an asynchronous socket channel.

The new channel is created by invoking the method on the that created the group. If the group parameter is null then the resulting channel is created by the system-wide default provider, and bound to the default group.
Requires API level 26 (Android 8.0, Oreo)

Parameters
group AsynchronousChannelGroup!: The group to which the newly constructed channel should be bound, or null for the default group
Return
AsynchronousSocketChannel!: A new asynchronous socket channel
Exceptions
ShutdownChannelGroupException If the channel group is shutdown
IOException If an I/O error occurs

open

added in API level 26
open static fun open(): AsynchronousSocketChannel!

Opens an asynchronous socket channel.

This method returns an asynchronous socket channel that is bound to the default group.This method is equivalent to evaluating the expression:

 open((AsynchronousChannelGroup)null); 

Requires API level 26 (Android 8.0, Oreo)
Return
AsynchronousSocketChannel!: A new asynchronous socket channel
Exceptions
IOException If an I/O error occurs