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package java.nio.channels;
import java.nio.ByteBuffer;
import java.util.concurrent.Future;
An asynchronous channel that can read and write bytes.
Some channels may not allow more than one read or write to be outstanding at any given time. If a thread invokes a read method before a previous read operation has completed then a ReadPendingException will be thrown. Similarly, if a write method is invoked before a previous write has completed then WritePendingException is thrown. Whether or not other kinds of I/O operations may proceed concurrently with a read operation depends upon the type of the channel.
Note that ByteBuffers are not safe for use by multiple concurrent threads. When a read or write operation is initiated then care must be taken to ensure that the buffer is not accessed until the operation completes.
See Also: Since: 1.7
/**
* An asynchronous channel that can read and write bytes.
*
* <p> Some channels may not allow more than one read or write to be outstanding
* at any given time. If a thread invokes a read method before a previous read
* operation has completed then a {@link ReadPendingException} will be thrown.
* Similarly, if a write method is invoked before a previous write has completed
* then {@link WritePendingException} is thrown. Whether or not other kinds of
* I/O operations may proceed concurrently with a read operation depends upon
* the type of the channel.
*
* <p> Note that {@link java.nio.ByteBuffer ByteBuffers} are not safe for use by
* multiple concurrent threads. When a read or write operation is initiated then
* care must be taken to ensure that the buffer is not accessed until the
* operation completes.
*
* @see Channels#newInputStream(AsynchronousByteChannel)
* @see Channels#newOutputStream(AsynchronousByteChannel)
*
* @since 1.7
*/
public interface AsynchronousByteChannel
extends AsynchronousChannel
{
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 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.
Params: - dst –
The buffer into which bytes are to be transferred
- attachment – The object to attach to the I/O operation; can be
null - handler –
The completion handler
Type parameters: - <A> –
The type of the attachment
Throws: - 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 is associated with a
group that has terminated
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* <p> This method initiates an asynchronous read operation to read a
* sequence of bytes from this channel into the given buffer. The {@code
* 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 {@code -1} if no bytes could be
* read because the channel has reached end-of-stream.
*
* <p> The read operation may read up to <i>r</i> bytes from the channel,
* where <i>r</i> is the number of bytes remaining in the buffer, that is,
* {@code dst.remaining()} at the time that the read is attempted. Where
* <i>r</i> is 0, the read operation completes immediately with a result of
* {@code 0} without initiating an I/O operation.
*
* <p> Suppose that a byte sequence of length <i>n</i> is read, where
* {@code 0} {@code <} <i>n</i> {@code <=} <i>r</i>.
* This byte sequence will be transferred into the buffer so that the first
* byte in the sequence is at index <i>p</i> and the last byte is at index
* <i>p</i> {@code +} <i>n</i> {@code -} {@code 1},
* where <i>p</i> is the buffer's position at the moment the read is
* performed. Upon completion the buffer's position will be equal to
* <i>p</i> {@code +} <i>n</i>; its limit will not have changed.
*
* <p> 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.
*
* <p> 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 {@link ReadPendingException} will be thrown.
*
* @param <A>
* The type of the attachment
* @param dst
* The buffer into which bytes are to be transferred
* @param attachment
* The object to attach to the I/O operation; can be {@code null}
* @param handler
* The completion handler
*
* @throws IllegalArgumentException
* If the buffer is read-only
* @throws ReadPendingException
* If the channel does not allow more than one read to be outstanding
* and a previous read has not completed
* @throws ShutdownChannelGroupException
* If the channel is associated with a {@link AsynchronousChannelGroup
* group} that has terminated
*/
<A> void read(ByteBuffer dst,
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 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.
Params: - dst –
The buffer into which bytes are to be transferred
Throws: - 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
Returns: A Future representing the result of the operation
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* <p> 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 {@link
* #read(ByteBuffer,Object,CompletionHandler)
* read(ByteBuffer,Object,CompletionHandler)} method except that instead
* of specifying a completion handler, this method returns a {@code Future}
* representing the pending result. The {@code Future}'s {@link Future#get()
* get} method returns the number of bytes read or {@code -1} if no bytes
* could be read because the channel has reached end-of-stream.
*
* @param dst
* The buffer into which bytes are to be transferred
*
* @return A Future representing the result of the operation
*
* @throws IllegalArgumentException
* If the buffer is read-only
* @throws ReadPendingException
* If the channel does not allow more than one read to be outstanding
* and a previous read has not completed
*/
Future<Integer> read(ByteBuffer dst);
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 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.
Params: - src –
The buffer from which bytes are to be retrieved
- attachment – The object to attach to the I/O operation; can be
null - handler –
The completion handler object
Type parameters: - <A> –
The type of the attachment
Throws: - 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 is associated with a
group that has terminated
/**
* Writes a sequence of bytes to this channel from the given buffer.
*
* <p> This method initiates an asynchronous write operation to write a
* sequence of bytes to this channel from the given buffer. The {@code
* 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.
*
* <p> The write operation may write up to <i>r</i> bytes to the channel,
* where <i>r</i> is the number of bytes remaining in the buffer, that is,
* {@code src.remaining()} at the time that the write is attempted. Where
* <i>r</i> is 0, the write operation completes immediately with a result of
* {@code 0} without initiating an I/O operation.
*
* <p> Suppose that a byte sequence of length <i>n</i> is written, where
* {@code 0} {@code <} <i>n</i> {@code <=} <i>r</i>.
* This byte sequence will be transferred from the buffer starting at index
* <i>p</i>, where <i>p</i> is the buffer's position at the moment the
* write is performed; the index of the last byte written will be
* <i>p</i> {@code +} <i>n</i> {@code -} {@code 1}.
* Upon completion the buffer's position will be equal to
* <i>p</i> {@code +} <i>n</i>; its limit will not have changed.
*
* <p> 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.
*
* <p> 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 {@link WritePendingException} will be thrown.
*
* @param <A>
* The type of the attachment
* @param src
* The buffer from which bytes are to be retrieved
* @param attachment
* The object to attach to the I/O operation; can be {@code null}
* @param 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 completed
* @throws ShutdownChannelGroupException
* If the channel is associated with a {@link AsynchronousChannelGroup
* group} that has terminated
*/
<A> void write(ByteBuffer src,
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 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.
Params: - src –
The buffer from which bytes are to be retrieved
Throws: - WritePendingException –
If the channel does not allow more than one write to be outstanding
and a previous write has not completed
Returns: A Future representing the result of the operation
/**
* Writes a sequence of bytes to this channel from the given buffer.
*
* <p> 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 {@link
* #write(ByteBuffer,Object,CompletionHandler)
* write(ByteBuffer,Object,CompletionHandler)} method except that instead
* of specifying a completion handler, this method returns a {@code Future}
* representing the pending result. The {@code Future}'s {@link Future#get()
* get} method returns the number of bytes written.
*
* @param src
* The buffer from which bytes are to be retrieved
*
* @return 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 completed
*/
Future<Integer> write(ByteBuffer src);
}