Closeable
, AutoCloseable
, AsynchronousByteChannel
, AsynchronousChannel
, Channel
, NetworkChannel
public abstract class AsynchronousSocketChannel extends Object implements AsynchronousByteChannel, NetworkChannel
Asynchronous socket channels are created in one of two ways. A newly-created AsynchronousSocketChannel
is created by invoking one of the open
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 getRemoteAddress
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:
Additional (implementation specific) options may also be supported.
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
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 InterruptedByTimeoutException
. 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.
Modifier | Constructor | Description |
---|---|---|
protected |
Initializes a new instance of this class. |
Modifier and Type | Method | Description |
---|---|---|
abstract AsynchronousSocketChannel |
bind |
Binds the channel's socket to a local address. |
abstract Future |
connect |
Connects this channel. |
abstract <A> void |
connect |
Connects this channel. |
abstract SocketAddress |
getLocalAddress() |
Returns the socket address that this channel's socket is bound to. |
abstract SocketAddress |
getRemoteAddress() |
Returns the remote address to which this channel's socket is connected. |
static AsynchronousSocketChannel |
open() |
Opens an asynchronous socket channel. |
static AsynchronousSocketChannel |
open |
Opens an asynchronous socket channel. |
final AsynchronousChannelProvider |
provider() |
Returns the provider that created this channel. |
abstract Future |
read |
Reads a sequence of bytes from this channel into the given buffer. |
abstract <A> void |
read |
Reads a sequence of bytes from this channel into a subsequence of the given buffers. |
abstract <A> void |
read |
Reads a sequence of bytes from this channel into the given buffer. |
final <A> void |
read |
Reads a sequence of bytes from this channel into the given buffer. |
abstract <T> AsynchronousSocketChannel |
setOption |
Sets the value of a socket option. |
abstract AsynchronousSocketChannel |
shutdownInput() |
Shutdown the connection for reading without closing the channel. |
abstract AsynchronousSocketChannel |
shutdownOutput() |
Shutdown the connection for writing without closing the channel. |
abstract Future |
write |
Writes a sequence of bytes to this channel from the given buffer. |
abstract <A> void |
write |
Writes a sequence of bytes to this channel from a subsequence of the given buffers. |
abstract <A> void |
write |
Writes a sequence of bytes to this channel from the given buffer. |
final <A> void |
write |
Writes a sequence of bytes to this channel from the given buffer. |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
close
getOption, supportedOptions
protected AsynchronousSocketChannel(AsynchronousChannelProvider provider)
provider
- The provider that created this channelpublic final AsynchronousChannelProvider provider()
public static AsynchronousSocketChannel open(AsynchronousChannelGroup group) throws IOException
The new channel is created by invoking the openAsynchronousSocketChannel
method on the AsynchronousChannelProvider
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.
group
- The group to which the newly constructed channel should be bound, or null
for the default groupShutdownChannelGroupException
- If the channel group is shutdownIOException
- If an I/O error occurspublic static AsynchronousSocketChannel open() throws IOException
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);
IOException
- If an I/O error occurspublic abstract AsynchronousSocketChannel bind(SocketAddress local) throws IOException
NetworkChannel
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. If the local
parameter has the value null
then the socket will be bound to an address that is assigned automatically.
bind
in interface NetworkChannel
local
- The address to bind the socket, or null
to bind the socket to an automatically assigned socket addressConnectionPendingException
- If a connection operation is already in progress on this channelAlreadyBoundException
- If the socket is already boundUnsupportedAddressTypeException
- If the type of the given address is not supportedClosedChannelException
- If the channel is closedIOException
- If some other I/O error occursSecurityException
- If a security manager has been installed and its checkListen
method denies the operationpublic abstract <T> AsynchronousSocketChannel setOption(SocketOption<T> name, T value) throws IOException
NetworkChannel
setOption
in interface NetworkChannel
T
- The type of the socket option valuename
- The socket optionvalue
- The value of the socket option. A value of null
may be a valid value for some socket options.IllegalArgumentException
- If the value is not a valid value for this socket optionClosedChannelException
- If this channel is closedIOException
- If an I/O error occurspublic abstract AsynchronousSocketChannel shutdownInput() throws IOException
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.
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurspublic abstract AsynchronousSocketChannel shutdownOutput() throws IOException
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.
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurspublic abstract SocketAddress getRemoteAddress() throws IOException
Where the channel is bound and connected to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress
.
null
if the channel's socket is not connectedClosedChannelException
- If the channel is closedIOException
- If an I/O error occurspublic abstract <A> void connect(SocketAddress remote, A attachment, CompletionHandler<Void,? super A> handler)
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 Socket
class. That is, if a security manager has been installed then this method verifies that its checkConnect
method permits connecting to the address and port number of the given remote endpoint.
A
- The type of the attachmentremote
- The remote address to which this channel is to be connectedattachment
- The object to attach to the I/O operation; can be null
handler
- The handler for consuming the resultUnresolvedAddressException
- If the given remote address is not fully resolvedUnsupportedAddressTypeException
- If the type of the given remote address is not supportedAlreadyConnectedException
- If this channel is already connectedConnectionPendingException
- If a connection operation is already in progress on this channelShutdownChannelGroupException
- If the channel group has terminatedSecurityException
- If a security manager has been installed and it does not permit access to the given remote endpointpublic abstract Future<Void> connect(SocketAddress remote)
This method initiates an operation to connect this channel. This method behaves in exactly the same manner as the connect(SocketAddress, Object, CompletionHandler)
method except that instead of specifying a completion handler, this method returns a
Future
representing the pending result. The Future
's get
method returns null
on successful completion.
remote
- The remote address to which this channel is to be connectedFuture
object representing the pending resultUnresolvedAddressException
- If the given remote address is not fully resolvedUnsupportedAddressTypeException
- If the type of the given remote address is not supportedAlreadyConnectedException
- If this channel is already connectedConnectionPendingException
- If a connection operation is already in progress on this channelSecurityException
- If a security manager has been installed and it does not permit access to the given remote endpointpublic abstract <A> void read(ByteBuffer dst, long timeout, TimeUnit unit, A attachment, CompletionHandler<Integer,? super A> handler)
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 InterruptedByTimeoutException
. 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 AsynchronousByteChannel.read(ByteBuffer,Object,CompletionHandler)
method.
A
- The type of the attachmentdst
- The buffer into which bytes are to be transferredtimeout
- The maximum time for the I/O operation to completeunit
- The time unit of the timeout
argumentattachment
- The object to attach to the I/O operation; can be null
handler
- The handler for consuming the resultIllegalArgumentException
- If the buffer is read-onlyReadPendingException
- If a read operation is already in progress on this channelNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic final <A> void read(ByteBuffer dst, A attachment, CompletionHandler<Integer,? super A> handler)
AsynchronousByteChannel
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.
The read operation may read up to r bytes from the channel, where r is the number of bytes remaining in the buffer, that is, dst.remaining()
at the time that the read is attempted. Where r is 0, the read operation completes immediately with a result of 0
without initiating an I/O operation.
Suppose that a byte sequence of length n is read, where 0
<
n <=
r. This byte sequence will be transferred into the buffer so that the first byte in the sequence is at index p and the last byte is at index p +
n -
1
, where p is the buffer's position at the moment the read is performed. Upon completion the buffer's position will be equal to p +
n; its limit will not have changed.
Buffers are not safe for use by multiple concurrent threads so care should be taken to not access the buffer until the operation has completed.
This method may be invoked at any time. Some channel types may not allow more than one read to be outstanding at any given time. If a thread initiates a read operation before a previous read operation has completed then a ReadPendingException
will be thrown.
read
in interface AsynchronousByteChannel
A
- The type of the attachmentdst
- The buffer into which bytes are to be transferredattachment
- The object to attach to the I/O operation; can be null
handler
- The completion handlerIllegalArgumentException
- If the buffer is read-onlyReadPendingException
- If the channel does not allow more than one read to be outstanding and a previous read has not completedNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic abstract Future<Integer> read(ByteBuffer dst)
AsynchronousByteChannel
This method initiates an asynchronous read operation to read a sequence of bytes from this channel into the given buffer. The method behaves in exactly the same manner as the read(ByteBuffer,Object,CompletionHandler)
method except that instead of specifying a completion handler, this method returns a Future
representing the pending result. The Future
's get
method returns the number of bytes read or -1
if no bytes could be read because the channel has reached end-of-stream.
read
in interface AsynchronousByteChannel
dst
- The buffer into which bytes are to be transferredIllegalArgumentException
- If the buffer is read-onlyReadPendingException
- If the channel does not allow more than one read to be outstanding and a previous read has not completedNotYetConnectedException
- If this channel is not yet connectedpublic abstract <A> void read(ByteBuffer[] dsts, int offset, int length, long timeout, TimeUnit unit, A attachment, CompletionHandler<Long,? super A> handler)
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()
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 InterruptedByTimeoutException
. 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.
A
- The type of the attachmentdsts
- The buffers into which bytes are to be transferredoffset
- 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
- The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset
timeout
- The maximum time for the I/O operation to completeunit
- The time unit of the timeout
argumentattachment
- The object to attach to the I/O operation; can be null
handler
- The handler for consuming the resultIndexOutOfBoundsException
- If the pre-conditions for the offset
and length
parameter aren't metIllegalArgumentException
- If the buffer is read-onlyReadPendingException
- If a read operation is already in progress on this channelNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic abstract <A> void write(ByteBuffer src, long timeout, TimeUnit unit, A attachment, CompletionHandler<Integer,? super A> handler)
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 InterruptedByTimeoutException
. 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 AsynchronousByteChannel.write(ByteBuffer,Object,CompletionHandler)
method.
A
- The type of the attachmentsrc
- The buffer from which bytes are to be retrievedtimeout
- The maximum time for the I/O operation to completeunit
- The time unit of the timeout
argumentattachment
- The object to attach to the I/O operation; can be null
handler
- The handler for consuming the resultWritePendingException
- If a write operation is already in progress on this channelNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic final <A> void write(ByteBuffer src, A attachment, CompletionHandler<Integer,? super A> handler)
AsynchronousByteChannel
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.
The write operation may write up to r bytes to the channel, where r is the number of bytes remaining in the buffer, that is, src.remaining()
at the time that the write is attempted. Where r is 0, the write operation completes immediately with a result of 0
without initiating an I/O operation.
Suppose that a byte sequence of length n is written, where 0
<
n <=
r. This byte sequence will be transferred from the buffer starting at index p, where p is the buffer's position at the moment the write is performed; the index of the last byte written will be p +
n -
1
. Upon completion the buffer's position will be equal to p +
n; its limit will not have changed.
Buffers are not safe for use by multiple concurrent threads so care should be taken to not access the buffer until the operation has completed.
This method may be invoked at any time. Some channel types may not allow more than one write to be outstanding at any given time. If a thread initiates a write operation before a previous write operation has completed then a WritePendingException
will be thrown.
write
in interface AsynchronousByteChannel
A
- The type of the attachmentsrc
- The buffer from which bytes are to be retrievedattachment
- The object to attach to the I/O operation; can be null
handler
- The completion handler objectWritePendingException
- If the channel does not allow more than one write to be outstanding and a previous write has not completedNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic abstract Future<Integer> write(ByteBuffer src)
AsynchronousByteChannel
This method initiates an asynchronous write operation to write a sequence of bytes to this channel from the given buffer. The method behaves in exactly the same manner as the write(ByteBuffer,Object,CompletionHandler)
method except that instead of specifying a completion handler, this method returns a Future
representing the pending result. The Future
's get
method returns the number of bytes written.
write
in interface AsynchronousByteChannel
src
- The buffer from which bytes are to be retrievedWritePendingException
- If the channel does not allow more than one write to be outstanding and a previous write has not completedNotYetConnectedException
- If this channel is not yet connectedpublic abstract <A> void write(ByteBuffer[] srcs, int offset, int length, long timeout, TimeUnit unit, A attachment, CompletionHandler<Long,? super A> handler)
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()
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 InterruptedByTimeoutException
. 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.
A
- The type of the attachmentsrcs
- The buffers from which bytes are to be retrievedoffset
- 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
- The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
timeout
- The maximum time for the I/O operation to completeunit
- The time unit of the timeout
argumentattachment
- The object to attach to the I/O operation; can be null
handler
- The handler for consuming the resultIndexOutOfBoundsException
- If the pre-conditions for the offset
and length
parameter aren't metWritePendingException
- If a write operation is already in progress on this channelNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminatedpublic abstract SocketAddress getLocalAddress() throws IOException
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.
getLocalAddress
in interface NetworkChannel
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 boundClosedChannelException
- If the channel is closedIOException
- If an I/O error occurs
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/channels/AsynchronousSocketChannel.html