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/*
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* Copyright (c) 2000, 2006, 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.io.IOException;
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import java.nio.ByteBuffer;
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/**
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* A channel that can read bytes into a sequence of buffers.
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*
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* <p> A <i>scattering</i> read operation reads, in a single invocation, a
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* sequence of bytes into one or more of a given sequence of buffers.
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* Scattering reads are often useful when implementing network protocols or
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* file formats that, for example, group data into segments consisting of one
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* or more fixed-length headers followed by a variable-length body. Similar
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* <i>gathering</i> write operations are defined in the {@link
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* GatheringByteChannel} interface. </p>
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*
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*
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* @author Mark Reinhold
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* @author JSR-51 Expert Group
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* @since 1.4
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*/
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public interface ScatteringByteChannel
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extends ReadableByteChannel
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{
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/**
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* Reads a sequence of bytes from this channel into a subsequence of the
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* given buffers.
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*
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* <p> An invocation of this method attempts to read up to <i>r</i> bytes
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* from this channel, where <i>r</i> is the total number of bytes remaining
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* the specified subsequence of the given buffer array, that is,
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*
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* <blockquote><pre>
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* dsts[offset].remaining()
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* + dsts[offset+1].remaining()
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* + ... + dsts[offset+length-1].remaining()</pre></blockquote>
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*
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* at the moment that this method is invoked.
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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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* <tt>0</tt> <tt><=</tt> <i>n</i> <tt><=</tt> <i>r</i>.
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* Up to the first <tt>dsts[offset].remaining()</tt> bytes of this sequence
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* are transferred into buffer <tt>dsts[offset]</tt>, up to the next
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* <tt>dsts[offset+1].remaining()</tt> bytes are transferred into buffer
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* <tt>dsts[offset+1]</tt>, and so forth, until the entire byte sequence
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* is transferred into the given buffers. As many bytes as possible are
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* transferred into each buffer, hence the final position of each updated
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* buffer, except the last updated buffer, is guaranteed to be equal to
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* that buffer's limit.
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*
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* <p> This method may be invoked at any time. If another thread has
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* already initiated a read operation upon this channel, however, then an
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* invocation of this method will block until the first operation is
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* complete. </p>
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*
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* @param dsts
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* The buffers into which bytes are to be transferred
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*
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* @param offset
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* The offset within the buffer array of the first buffer into
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* which bytes are to be transferred; must be non-negative and no
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* larger than <tt>dsts.length</tt>
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*
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* @param length
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* The maximum number of buffers to be accessed; must be
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* non-negative and no larger than
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* <tt>dsts.length</tt> - <tt>offset</tt>
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*
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* @return The number of bytes read, possibly zero,
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* or <tt>-1</tt> if the channel has reached end-of-stream
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*
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* @throws IndexOutOfBoundsException
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* If the preconditions on the <tt>offset</tt> and <tt>length</tt>
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* parameters do not hold
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*
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* @throws NonReadableChannelException
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* If this channel was not opened for reading
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*
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* @throws ClosedChannelException
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* If this channel is closed
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*
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* @throws AsynchronousCloseException
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* If another thread closes this channel
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* while the read operation is in progress
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*
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* @throws ClosedByInterruptException
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* If another thread interrupts the current thread
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* while the read operation is in progress, thereby
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* closing the channel and setting the current thread's
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* interrupt status
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*
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* @throws IOException
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* If some other I/O error occurs
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*/
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public long read(ByteBuffer[] dsts, int offset, int length)
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throws IOException;
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/**
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* Reads a sequence of bytes from this channel into the given buffers.
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*
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* <p> An invocation of this method of the form <tt>c.read(dsts)</tt>
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* behaves in exactly the same manner as the invocation
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*
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* <blockquote><pre>
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* c.read(dsts, 0, dsts.length);</pre></blockquote>
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*
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* @param dsts
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* The buffers into which bytes are to be transferred
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*
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* @return The number of bytes read, possibly zero,
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* or <tt>-1</tt> if the channel has reached end-of-stream
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*
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* @throws NonReadableChannelException
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* If this channel was not opened for reading
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*
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* @throws ClosedChannelException
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* If this channel is closed
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*
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* @throws AsynchronousCloseException
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* If another thread closes this channel
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* while the read operation is in progress
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*
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* @throws ClosedByInterruptException
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* If another thread interrupts the current thread
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* while the read operation is in progress, thereby
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* closing the channel and setting the current thread's
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* interrupt status
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*
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* @throws IOException
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* If some other I/O error occurs
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*/
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public long read(ByteBuffer[] dsts) throws IOException;
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}
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