/* * 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 <i>scattering</i> 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</i> 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 <i>r</i> bytes     * from this channel, where <i>r</i> is the total number of bytes remaining     * the specified subsequence of the given buffer array, that is,     *     * <blockquote><pre>     * dsts[offset].remaining()     *     + dsts[offset+1].remaining()     *     + ... + dsts[offset+length-1].remaining()</pre></blockquote>     *     * at the moment that this method is invoked.     *     * <p> Suppose that a byte sequence of length <i>n</i> is read, where     * <tt>0</tt>&nbsp;<tt>&lt;=</tt>&nbsp;<i>n</i>&nbsp;<tt>&lt;=</tt>&nbsp;<i>r</i>.     * Up to the first <tt>dsts[offset].remaining()</tt> bytes of this sequence     * are transferred into buffer <tt>dsts[offset]</tt>, up to the next     * <tt>dsts[offset+1].remaining()</tt> bytes are transferred into buffer     * <tt>dsts[offset+1]</tt>, 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</tt>     *     * @param  length     *         The maximum number of buffers to be accessed; must be     *         non-negative and no larger than     *         <tt>dsts.length</tt>&nbsp;-&nbsp;<tt>offset</tt>     *     * @return The number of bytes read, possibly zero,     *         or <tt>-1</tt> if the channel has reached end-of-stream     *     * @throws  IndexOutOfBoundsException     *          If the preconditions on the <tt>offset</tt> and <tt>length</tt>     *          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 <tt>c.read(dsts)</tt>     * behaves in exactly the same manner as the invocation     *     * <blockquote><pre>     * c.read(dsts, 0, dsts.length);</pre></blockquote>     *     * @param  dsts     *         The buffers into which bytes are to be transferred     *     * @return The number of bytes read, possibly zero,     *         or <tt>-1</tt> 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; }