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_SNDBUFThe size of the socket send buffer SO_RCVBUFThe size of the socket receive buffer SO_KEEPALIVEKeep connection alive SO_REUSEADDRRe-use address TCP_NODELAYDisable 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 and Description |
|---|---|
protected |
AsynchronousSocketChannel(AsynchronousChannelProvider provider)
Initializes a new instance of this class.
|
| Modifier and Type | Method and Description |
|---|---|
abstract AsynchronousSocketChannel |
bind(SocketAddress local)
Binds the channel's socket to a local address.
|
abstract Future<Void> |
connect(SocketAddress remote)
Connects this channel.
|
abstract <A> void |
connect(SocketAddress remote,
A attachment,
CompletionHandler<Void,? super A> handler)
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(AsynchronousChannelGroup group)
Opens an asynchronous socket channel.
|
AsynchronousChannelProvider |
provider()
Returns the provider that created this channel.
|
abstract Future<Integer> |
read(ByteBuffer dst)
Reads a sequence of bytes from this channel into the given buffer.
|
abstract <A> void |
read(ByteBuffer[] dsts,
int offset,
int length,
long timeout,
TimeUnit unit,
A attachment,
CompletionHandler<Long,? super A> handler)
Reads a sequence of bytes from this channel into a subsequence of the
given buffers.
|
<A> void |
read(ByteBuffer dst,
A attachment,
CompletionHandler<Integer,? super A> handler)
Reads a sequence of bytes from this channel into the given buffer.
|
abstract <A> void |
read(ByteBuffer dst,
long timeout,
TimeUnit unit,
A attachment,
CompletionHandler<Integer,? super A> handler)
Reads a sequence of bytes from this channel into the given buffer.
|
abstract <T> AsynchronousSocketChannel |
setOption(SocketOption<T> name,
T value)
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<Integer> |
write(ByteBuffer src)
Writes a sequence of bytes to this channel from the given buffer.
|
abstract <A> void |
write(ByteBuffer[] srcs,
int offset,
int length,
long timeout,
TimeUnit unit,
A attachment,
CompletionHandler<Long,? super A> handler)
Writes a sequence of bytes to this channel from a subsequence of the given
buffers.
|
<A> void |
write(ByteBuffer src,
A attachment,
CompletionHandler<Integer,? super A> handler)
Writes a sequence of bytes to this channel from the given buffer.
|
abstract <A> void |
write(ByteBuffer src,
long timeout,
TimeUnit unit,
A attachment,
CompletionHandler<Integer,? super A> handler)
Writes a sequence of bytes to this channel from the given buffer.
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitclosegetOption, supportedOptionsprotected 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 NetworkChannellocal - 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 operationNetworkChannel.getLocalAddress()public abstract <T> AsynchronousSocketChannel setOption(SocketOption<T> name, T value) throws IOException
NetworkChannelsetOption in interface NetworkChannelT - 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 occursStandardSocketOptionspublic 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 nullhandler - 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 endpointgetRemoteAddress()public 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 nullhandler - 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 AsynchronousByteChannelA - 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 nullhandler - 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 AsynchronousByteChanneldst - 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.lengthlength - The maximum number of buffers to be accessed; must be non-negative
and no larger than dsts.length - offsettimeout - 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 nullhandler - 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 nullhandler - 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 AsynchronousByteChannelA - 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 nullhandler - 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 AsynchronousByteChannelsrc - 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.lengthlength - The maximum number of buffers to be accessed; must be non-negative
and no larger than srcs.length - offsettimeout - 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 nullhandler - 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 NetworkChannelSocketAddress 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 Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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