214 lines
10 KiB
Java
214 lines
10 KiB
Java
/*
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* Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.nio.channels;
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import java.nio.ByteBuffer;
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import java.util.concurrent.Future;
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/**
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* An asynchronous channel that can read and write bytes.
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*
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* <p> Some channels may not allow more than one read or write to be outstanding
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* at any given time. If a thread invokes a read method before a previous read
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* operation has completed then a {@link ReadPendingException} will be thrown.
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* Similarly, if a write method is invoked before a previous write has completed
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* then {@link WritePendingException} is thrown. Whether or not other kinds of
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* I/O operations may proceed concurrently with a read operation depends upon
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* the type of the channel.
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*
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* <p> Note that {@link java.nio.ByteBuffer ByteBuffers} are not safe for use by
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* multiple concurrent threads. When a read or write operation is initiated then
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* care must be taken to ensure that the buffer is not accessed until the
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* operation completes.
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*
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* @see Channels#newInputStream(AsynchronousByteChannel)
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* @see Channels#newOutputStream(AsynchronousByteChannel)
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*
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* @since 1.7
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*/
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public interface AsynchronousByteChannel
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extends AsynchronousChannel
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{
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/**
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* Reads a sequence of bytes from this channel into the given buffer.
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*
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* <p> This method initiates an asynchronous read operation to read a
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* sequence of bytes from this channel into the given buffer. The {@code
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* handler} parameter is a completion handler that is invoked when the read
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* operation completes (or fails). The result passed to the completion
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* handler is the number of bytes read or {@code -1} if no bytes could be
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* read because the channel has reached end-of-stream.
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*
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* <p> The read operation may read up to <i>r</i> bytes from the channel,
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* where <i>r</i> is the number of bytes remaining in the buffer, that is,
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* {@code dst.remaining()} at the time that the read is attempted. Where
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* <i>r</i> is 0, the read operation completes immediately with a result of
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* {@code 0} without initiating an I/O operation.
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*
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* <p> Suppose that a byte sequence of length <i>n</i> is read, where
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* {@code 0} {@code <} <i>n</i> {@code <=} <i>r</i>.
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* This byte sequence will be transferred into the buffer so that the first
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* byte in the sequence is at index <i>p</i> and the last byte is at index
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* <i>p</i> {@code +} <i>n</i> {@code -} {@code 1},
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* where <i>p</i> is the buffer's position at the moment the read is
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* performed. Upon completion the buffer's position will be equal to
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* <i>p</i> {@code +} <i>n</i>; its limit will not have changed.
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*
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* <p> Buffers are not safe for use by multiple concurrent threads so care
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* should be taken to not access the buffer until the operation has
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* completed.
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*
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* <p> This method may be invoked at any time. Some channel types may not
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* allow more than one read to be outstanding at any given time. If a thread
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* initiates a read operation before a previous read operation has
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* completed then a {@link ReadPendingException} will be thrown.
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*
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* @param <A>
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* The type of the attachment
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* @param dst
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* The buffer into which bytes are to be transferred
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* @param attachment
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* The object to attach to the I/O operation; can be {@code null}
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* @param handler
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* The completion handler
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*
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* @throws IllegalArgumentException
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* If the buffer is read-only
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* @throws ReadPendingException
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* If the channel does not allow more than one read to be outstanding
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* and a previous read has not completed
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* @throws ShutdownChannelGroupException
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* If the channel is associated with a {@link AsynchronousChannelGroup
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* group} that has terminated
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*/
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<A> void read(ByteBuffer dst,
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A attachment,
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CompletionHandler<Integer,? super A> handler);
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/**
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* Reads a sequence of bytes from this channel into the given buffer.
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*
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* <p> This method initiates an asynchronous read operation to read a
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* sequence of bytes from this channel into the given buffer. The method
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* behaves in exactly the same manner as the {@link
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* #read(ByteBuffer,Object,CompletionHandler)
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* read(ByteBuffer,Object,CompletionHandler)} method except that instead
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* of specifying a completion handler, this method returns a {@code Future}
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* representing the pending result. The {@code Future}'s {@link Future#get()
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* get} method returns the number of bytes read or {@code -1} if no bytes
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* could be read because the channel has reached end-of-stream.
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*
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* @param dst
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* The buffer into which bytes are to be transferred
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*
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* @return A Future representing the result of the operation
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*
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* @throws IllegalArgumentException
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* If the buffer is read-only
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* @throws ReadPendingException
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* If the channel does not allow more than one read to be outstanding
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* and a previous read has not completed
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*/
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Future<Integer> read(ByteBuffer dst);
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/**
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* Writes a sequence of bytes to this channel from the given buffer.
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*
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* <p> This method initiates an asynchronous write operation to write a
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* sequence of bytes to this channel from the given buffer. The {@code
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* handler} parameter is a completion handler that is invoked when the write
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* operation completes (or fails). The result passed to the completion
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* handler is the number of bytes written.
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*
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* <p> The write operation may write up to <i>r</i> bytes to the channel,
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* where <i>r</i> is the number of bytes remaining in the buffer, that is,
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* {@code src.remaining()} at the time that the write is attempted. Where
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* <i>r</i> is 0, the write operation completes immediately with a result of
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* {@code 0} without initiating an I/O operation.
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*
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* <p> Suppose that a byte sequence of length <i>n</i> is written, where
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* {@code 0} {@code <} <i>n</i> {@code <=} <i>r</i>.
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* This byte sequence will be transferred from the buffer starting at index
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* <i>p</i>, where <i>p</i> is the buffer's position at the moment the
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* write is performed; the index of the last byte written will be
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* <i>p</i> {@code +} <i>n</i> {@code -} {@code 1}.
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* Upon completion the buffer's position will be equal to
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* <i>p</i> {@code +} <i>n</i>; its limit will not have changed.
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*
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* <p> Buffers are not safe for use by multiple concurrent threads so care
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* should be taken to not access the buffer until the operation has
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* completed.
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*
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* <p> This method may be invoked at any time. Some channel types may not
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* allow more than one write to be outstanding at any given time. If a thread
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* initiates a write operation before a previous write operation has
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* completed then a {@link WritePendingException} will be thrown.
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*
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* @param <A>
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* The type of the attachment
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* @param src
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* The buffer from which bytes are to be retrieved
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* @param attachment
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* The object to attach to the I/O operation; can be {@code null}
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* @param handler
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* The completion handler object
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*
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* @throws WritePendingException
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* If the channel does not allow more than one write to be outstanding
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* and a previous write has not completed
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* @throws ShutdownChannelGroupException
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* If the channel is associated with a {@link AsynchronousChannelGroup
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* group} that has terminated
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*/
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<A> void write(ByteBuffer src,
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A attachment,
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CompletionHandler<Integer,? super A> handler);
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/**
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* Writes a sequence of bytes to this channel from the given buffer.
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*
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* <p> This method initiates an asynchronous write operation to write a
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* sequence of bytes to this channel from the given buffer. The method
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* behaves in exactly the same manner as the {@link
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* #write(ByteBuffer,Object,CompletionHandler)
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* write(ByteBuffer,Object,CompletionHandler)} method except that instead
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* of specifying a completion handler, this method returns a {@code Future}
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* representing the pending result. The {@code Future}'s {@link Future#get()
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* get} method returns the number of bytes written.
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*
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* @param src
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* The buffer from which bytes are to be retrieved
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*
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* @return A Future representing the result of the operation
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*
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* @throws WritePendingException
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* If the channel does not allow more than one write to be outstanding
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* and a previous write has not completed
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*/
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Future<Integer> write(ByteBuffer src);
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}
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