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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

 *

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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

     * {@code 0}&nbsp;{@code <=}&nbsp;<i>n</i>&nbsp;{@code <=}&nbsp;<i>r</i>.

     * Up to the first {@code dsts[offset].remaining()} bytes of this sequence

     * are transferred into buffer {@code dsts[offset]}, up to the next

     * {@code dsts[offset+1].remaining()} bytes are transferred into buffer

     * {@code 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 {@code dsts.length}

     *

     * @param  length

     *         The maximum number of buffers to be accessed; must be

     *         non-negative and no larger than

     *         {@code dsts.length} - {@code offset}

     *

     * @return The number of bytes read, possibly zero,

     *         or {@code -1} if the channel has reached end-of-stream

     *

     * @throws  IndexOutOfBoundsException

     *          If the preconditions on the {@code offset} and {@code 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 {@code c.read(dsts)}

     * 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 {@code -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;

}