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/* * @(#)ScatteringByteChannel.java 1.15 06/04/19 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ 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 * @version 1.15, 06/04/19 * @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> <tt><=</tt> <i>n</i> <tt><=</tt> <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> - <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; }