1 /*

     2  * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package java.nio.channels;

    27 

    28 import java.io.IOException;

    29 import java.nio.ByteBuffer;

    30 

    31 

    32 /**

    33  * A channel that can write bytes from a sequence of buffers.

    34  *

    35  * <p> A <i>gathering</i> write operation writes, in a single invocation, a

    36  * sequence of bytes from one or more of a given sequence of buffers.

    37  * Gathering writes are often useful when implementing network protocols or

    38  * file formats that, for example, group data into segments consisting of one

    39  * or more fixed-length headers followed by a variable-length body.  Similar

    40  * <i>scattering</i> read operations are defined in the {@link

    41  * ScatteringByteChannel} interface.  </p>

    42  *

    43  *

    44  * @author Mark Reinhold

    45  * @author JSR-51 Expert Group

    46  * @since 1.4

    47  */

    48 

    49 public interface GatheringByteChannel

    50     extends WritableByteChannel

    51 {

    52 

    53     /**

    54      * Writes a sequence of bytes to this channel from a subsequence of the

    55      * given buffers.

    56      *

    57      * <p> An attempt is made to write up to <i>r</i> bytes to this channel,

    58      * where <i>r</i> is the total number of bytes remaining in the specified

    59      * subsequence of the given buffer array, that is,

    60      *

    61      * <blockquote><pre>

    62      * srcs[offset].remaining()

    63      *     + srcs[offset+1].remaining()

    64      *     + ... + srcs[offset+length-1].remaining()</pre></blockquote>

    65      *

    66      * at the moment that this method is invoked.

    67      *

    68      * <p> Suppose that a byte sequence of length <i>n</i> is written, where

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

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

    71      * are written from buffer {@code srcs[offset]}, up to the next

    72      * {@code srcs[offset+1].remaining()} bytes are written from buffer

    73      * {@code srcs[offset+1]}, and so forth, until the entire byte sequence is

    74      * written.  As many bytes as possible are written from each buffer, hence

    75      * the final position of each updated buffer, except the last updated

    76      * buffer, is guaranteed to be equal to that buffer's limit.

    77      *

    78      * <p> Unless otherwise specified, a write operation will return only after

    79      * writing all of the <i>r</i> requested bytes.  Some types of channels,

    80      * depending upon their state, may write only some of the bytes or possibly

    81      * none at all.  A socket channel in non-blocking mode, for example, cannot

    82      * write any more bytes than are free in the socket's output buffer.

    83      *

    84      * <p> This method may be invoked at any time.  If another thread has

    85      * already initiated a write operation upon this channel, however, then an

    86      * invocation of this method will block until the first operation is

    87      * complete. </p>

    88      *

    89      * @param  srcs

    90      *         The buffers from which bytes are to be retrieved

    91      *

    92      * @param  offset

    93      *         The offset within the buffer array of the first buffer from

    94      *         which bytes are to be retrieved; must be non-negative and no

    95      *         larger than {@code srcs.length}

    96      *

    97      * @param  length

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

    99      *         non-negative and no larger than

   100      *         {@code srcs.length} - {@code offset}

   101      *

   102      * @return  The number of bytes written, possibly zero

   103      *

   104      * @throws  IndexOutOfBoundsException

   105      *          If the preconditions on the {@code offset} and {@code length}

   106      *          parameters do not hold

   107      *

   108      * @throws  NonWritableChannelException

   109      *          If this channel was not opened for writing

   110      *

   111      * @throws  ClosedChannelException

   112      *          If this channel is closed

   113      *

   114      * @throws  AsynchronousCloseException

   115      *          If another thread closes this channel

   116      *          while the write operation is in progress

   117      *

   118      * @throws  ClosedByInterruptException

   119      *          If another thread interrupts the current thread

   120      *          while the write operation is in progress, thereby

   121      *          closing the channel and setting the current thread's

   122      *          interrupt status

   123      *

   124      * @throws  IOException

   125      *          If some other I/O error occurs

   126      */

   127     public long write(ByteBuffer[] srcs, int offset, int length)

   128         throws IOException;

   129 

   130 

   131     /**

   132      * Writes a sequence of bytes to this channel from the given buffers.

   133      *

   134      * <p> An invocation of this method of the form {@code c.write(srcs)}

   135      * behaves in exactly the same manner as the invocation

   136      *

   137      * <blockquote><pre>

   138      * c.write(srcs, 0, srcs.length);</pre></blockquote>

   139      *

   140      * @param  srcs

   141      *         The buffers from which bytes are to be retrieved

   142      *

   143      * @return  The number of bytes written, possibly zero

   144      *

   145      * @throws  NonWritableChannelException

   146      *          If this channel was not opened for writing

   147      *

   148      * @throws  ClosedChannelException

   149      *          If this channel is closed

   150      *

   151      * @throws  AsynchronousCloseException

   152      *          If another thread closes this channel

   153      *          while the write operation is in progress

   154      *

   155      * @throws  ClosedByInterruptException

   156      *          If another thread interrupts the current thread

   157      *          while the write operation is in progress, thereby

   158      *          closing the channel and setting the current thread's

   159      *          interrupt status

   160      *

   161      * @throws  IOException

   162      *          If some other I/O error occurs

   163      */

   164     public long write(ByteBuffer[] srcs) throws IOException;

   165 

   166 }