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Java example source code file (ScatteringByteChannel.java)

This example Java source code file (ScatteringByteChannel.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

ioexception, nio, readablebytechannel, scatteringbytechannel

The ScatteringByteChannel.java Java example source code

/*
 * Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.nio.channels;

import java.io.IOException;
import java.nio.ByteBuffer;


/**
 * A channel that can read bytes into a sequence of buffers.
 *
 * <p> A scattering read operation reads, in a single invocation, a
 * sequence of bytes into one or more of a given sequence of buffers.
 * Scattering reads are often useful when implementing network protocols or
 * file formats that, for example, group data into segments consisting of one
 * or more fixed-length headers followed by a variable-length body.  Similar
 * <i>gathering write operations are defined in the {@link
 * GatheringByteChannel} interface.  </p>
 *
 *
 * @author Mark Reinhold
 * @author JSR-51 Expert Group
 * @since 1.4
 */

public interface ScatteringByteChannel
    extends ReadableByteChannel
{

    /**
     * Reads a sequence of bytes from this channel into a subsequence of the
     * given buffers.
     *
     * <p> An invocation of this method attempts to read up to r bytes
     * from this channel, where <i>r is the total number of bytes remaining
     * the specified subsequence of the given buffer array, that is,
     *
     * <blockquote>
     * dsts[offset].remaining()
     *     + dsts[offset+1].remaining()
     *     + ... + dsts[offset+length-1].remaining()</pre>
     *
     * at the moment that this method is invoked.
     *
     * <p> Suppose that a byte sequence of length n is read, where
     * <tt>0 <= n <= r.
     * Up to the first <tt>dsts[offset].remaining() bytes of this sequence
     * are transferred into buffer <tt>dsts[offset], up to the next
     * <tt>dsts[offset+1].remaining() bytes are transferred into buffer
     * <tt>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.
     *
     * <p> This method may be invoked at any time.  If another thread has
     * already initiated a read operation upon this channel, however, then an
     * invocation of this method will block until the first operation is
     * complete. </p>
     *
     * @param  dsts
     *         The buffers into which bytes are to be transferred
     *
     * @param  offset
     *         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 <tt>dsts.length
     *
     * @param  length
     *         The maximum number of buffers to be accessed; must be
     *         non-negative and no larger than
     *         <tt>dsts.length - offset
     *
     * @return The number of bytes read, possibly zero,
     *         or <tt>-1 if the channel has reached end-of-stream
     *
     * @throws  IndexOutOfBoundsException
     *          If the preconditions on the <tt>offset and length
     *          parameters do not hold
     *
     * @throws  NonReadableChannelException
     *          If this channel was not opened for reading
     *
     * @throws  ClosedChannelException
     *          If this channel is closed
     *
     * @throws  AsynchronousCloseException
     *          If another thread closes this channel
     *          while the read operation is in progress
     *
     * @throws  ClosedByInterruptException
     *          If another thread interrupts the current thread
     *          while the read operation is in progress, thereby
     *          closing the channel and setting the current thread's
     *          interrupt status
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public long read(ByteBuffer[] dsts, int offset, int length)
        throws IOException;

    /**
     * Reads a sequence of bytes from this channel into the given buffers.
     *
     * <p> An invocation of this method of the form c.read(dsts)
     * behaves in exactly the same manner as the invocation
     *
     * <blockquote>
     * c.read(dsts, 0, dsts.length);</pre>
     *
     * @param  dsts
     *         The buffers into which bytes are to be transferred
     *
     * @return The number of bytes read, possibly zero,
     *         or <tt>-1 if the channel has reached end-of-stream
     *
     * @throws  NonReadableChannelException
     *          If this channel was not opened for reading
     *
     * @throws  ClosedChannelException
     *          If this channel is closed
     *
     * @throws  AsynchronousCloseException
     *          If another thread closes this channel
     *          while the read operation is in progress
     *
     * @throws  ClosedByInterruptException
     *          If another thread interrupts the current thread
     *          while the read operation is in progress, thereby
     *          closing the channel and setting the current thread's
     *          interrupt status
     *
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public long read(ByteBuffer[] dsts) throws IOException;

}

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