Class AsynchronousSocketChannel
- All Implemented Interfaces:
Closeable
,AutoCloseable
,AsynchronousByteChannel
,AsynchronousChannel
,Channel
,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
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 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.
- Since:
- 1.7
-
Constructor Summary
ModifierConstructorDescriptionprotected
Initializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionabstract AsynchronousSocketChannel
bind
(SocketAddress local) Binds the channel's socket to a local address.connect
(SocketAddress remote) Connects this channel.abstract <A> void
connect
(SocketAddress remote, A attachment, CompletionHandler<Void, ? super A> handler) Connects this channel.abstract SocketAddress
Returns the socket address that this channel's socket is bound to.abstract SocketAddress
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.provider()
Returns the provider that created this channel.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.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.final <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 <T> AsynchronousSocketChannel
setOption
(SocketOption<T> name, T value) Sets the value of a socket option.abstract AsynchronousSocketChannel
Shutdown the connection for reading without closing the channel.abstract AsynchronousSocketChannel
Shutdown the connection for writing without closing the channel.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.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.final <A> void
write
(ByteBuffer src, A attachment, CompletionHandler<Integer, ? super A> handler) Writes a sequence of bytes to this channel from the given buffer.Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface java.nio.channels.AsynchronousChannel
close
Methods declared in interface java.nio.channels.NetworkChannel
getOption, supportedOptions
-
Constructor Details
-
AsynchronousSocketChannel
Initializes a new instance of this class.- Parameters:
provider
- The provider that created this channel
-
-
Method Details
-
provider
Returns the provider that created this channel.- Returns:
- The provider that created this channel
-
open
Opens an asynchronous socket channel.The new channel is created by invoking the
openAsynchronousSocketChannel
method on theAsynchronousChannelProvider
that created the group. If the group parameter isnull
then the resulting channel is created by the system-wide default provider, and bound to the default group.- Parameters:
group
- The group to which the newly constructed channel should be bound, ornull
for the default group- Returns:
- A new asynchronous socket channel
- Throws:
ShutdownChannelGroupException
- If the channel group is shutdownIOException
- If an I/O error occurs
-
open
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);
- Returns:
- A new asynchronous socket channel
- Throws:
IOException
- If an I/O error occurs
-
bind
Description copied from interface:NetworkChannel
Binds the channel's socket to a local address.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 valuenull
then the socket will be bound to an address that is assigned automatically.- Specified by:
bind
in interfaceNetworkChannel
- Parameters:
local
- The address to bind the socket, ornull
to bind the socket to an automatically assigned socket address- Returns:
- This channel
- Throws:
ConnectionPendingException
- 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 itscheckListen
method denies the operation- See Also:
-
setOption
public abstract <T> AsynchronousSocketChannel setOption(SocketOption<T> name, T value) throws IOException Description copied from interface:NetworkChannel
Sets the value of a socket option.- Specified by:
setOption
in interfaceNetworkChannel
- Type Parameters:
T
- The type of the socket option value- Parameters:
name
- The socket optionvalue
- The value of the socket option. A value ofnull
may be a valid value for some socket options.- Returns:
- This channel
- Throws:
IllegalArgumentException
- If the value is not a valid value for this socket optionClosedChannelException
- If this channel is closedIOException
- If an I/O error occurs- See Also:
-
shutdownInput
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.- Returns:
- The channel
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurs
-
shutdownOutput
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.- Returns:
- The channel
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurs
-
getRemoteAddress
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
InetSocketAddress
.- Returns:
- The remote address;
null
if the channel's socket is not connected - Throws:
ClosedChannelException
- If the channel is closedIOException
- If an I/O error occurs
-
connect
public abstract <A> void connect(SocketAddress remote, A attachment, CompletionHandler<Void, ? super A> handler) 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
Socket
class. That is, if a security manager has been installed then this method verifies that itscheckConnect
method permits connecting to the address and port number of the given remote endpoint.- Type Parameters:
A
- The type of the attachment- Parameters:
remote
- The remote address to which this channel is to be connectedattachment
- The object to attach to the I/O operation; can benull
handler
- The handler for consuming the result- Throws:
UnresolvedAddressException
- 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 endpoint- See Also:
-
connect
Connects this channel.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 aFuture
representing the pending result. TheFuture
'sget
method returnsnull
on successful completion.- Parameters:
remote
- The remote address to which this channel is to be connected- Returns:
- A
Future
object representing the pending result - Throws:
UnresolvedAddressException
- 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 endpoint
-
read
public 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.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.- Type Parameters:
A
- The type of the attachment- Parameters:
dst
- The buffer into which bytes are to be transferredtimeout
- The maximum time for the I/O operation to completeunit
- The time unit of thetimeout
argumentattachment
- The object to attach to the I/O operation; can benull
handler
- The handler for consuming the result- Throws:
IllegalArgumentException
- 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 terminated
-
read
public final <A> void read(ByteBuffer dst, A attachment, CompletionHandler<Integer, ? super A> handler) Description copied from interface:AsynchronousByteChannel
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.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 of0
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.- Specified by:
read
in interfaceAsynchronousByteChannel
- Type Parameters:
A
- The type of the attachment- Parameters:
dst
- The buffer into which bytes are to be transferredattachment
- The object to attach to the I/O operation; can benull
handler
- The completion handler- Throws:
IllegalArgumentException
- 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 terminated
-
read
Description copied from interface:AsynchronousByteChannel
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 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 aFuture
representing the pending result. TheFuture
'sget
method returns the number of bytes read or-1
if no bytes could be read because the channel has reached end-of-stream.- Specified by:
read
in interfaceAsynchronousByteChannel
- Parameters:
dst
- The buffer into which bytes are to be transferred- Returns:
- A Future representing the result of the operation
- Throws:
IllegalArgumentException
- 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 connected
-
read
public 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. 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. Thehandler
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 firstdsts[offset].remaining()
bytes of this sequence are transferred into bufferdsts[offset]
, up to the nextdsts[offset+1].remaining()
bytes are transferred into bufferdsts[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.- Type Parameters:
A
- The type of the attachment- Parameters:
dsts
- 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 thandsts.length
length
- The maximum number of buffers to be accessed; must be non-negative and no larger thandsts.length - offset
timeout
- The maximum time for the I/O operation to completeunit
- The time unit of thetimeout
argumentattachment
- The object to attach to the I/O operation; can benull
handler
- The handler for consuming the result- Throws:
IndexOutOfBoundsException
- If the pre-conditions for theoffset
andlength
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 terminated
-
write
public 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.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.- Type Parameters:
A
- The type of the attachment- Parameters:
src
- The buffer from which bytes are to be retrievedtimeout
- The maximum time for the I/O operation to completeunit
- The time unit of thetimeout
argumentattachment
- The object to attach to the I/O operation; can benull
handler
- The handler for consuming the result- Throws:
WritePendingException
- If a write operation is already in progress on this channelNotYetConnectedException
- If this channel is not yet connectedShutdownChannelGroupException
- If the channel group has terminated
-
write
public final <A> void write(ByteBuffer src, A attachment, CompletionHandler<Integer, ? super A> handler) Description copied from interface:AsynchronousByteChannel
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.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 of0
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.- Specified by:
write
in interfaceAsynchronousByteChannel
- Type Parameters:
A
- The type of the attachment- Parameters:
src
- The buffer from which bytes are to be retrievedattachment
- The object to attach to the I/O operation; can benull
handler
- The completion handler object- Throws:
WritePendingException
- 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 terminated
-
write
Description copied from interface:AsynchronousByteChannel
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 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 aFuture
representing the pending result. TheFuture
'sget
method returns the number of bytes written.- Specified by:
write
in interfaceAsynchronousByteChannel
- Parameters:
src
- The buffer from which bytes are to be retrieved- Returns:
- A Future representing the result of the operation
- Throws:
WritePendingException
- 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 connected
-
write
public 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. 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. Thehandler
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 firstsrcs[offset].remaining()
bytes of this sequence are written from buffersrcs[offset]
, up to the nextsrcs[offset+1].remaining()
bytes are written from buffersrcs[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.- Type Parameters:
A
- The type of the attachment- Parameters:
srcs
- 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 thansrcs.length
length
- The maximum number of buffers to be accessed; must be non-negative and no larger thansrcs.length - offset
timeout
- The maximum time for the I/O operation to completeunit
- The time unit of thetimeout
argumentattachment
- The object to attach to the I/O operation; can benull
handler
- The handler for consuming the result- Throws:
IndexOutOfBoundsException
- If the pre-conditions for theoffset
andlength
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 terminated
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getLocalAddress
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 typeInetSocketAddress
.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, aSocketAddress
representing theloopback
address and the local port of the channel's socket is returned.- Specified by:
getLocalAddress
in interfaceNetworkChannel
- Returns:
- The
SocketAddress
that the socket is bound to, or theSocketAddress
representing the loopback address if denied by the security manager, ornull
if the channel's socket is not bound - Throws:
ClosedChannelException
- If the channel is closedIOException
- If an I/O error occurs
-