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 26package java.nio.channels; 27 28import java.io.IOException; 29import 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 49public 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 * <tt>0</tt> <tt><=</tt> <i>n</i> <tt><=</tt> <i>r</i>. 70 * Up to the first <tt>srcs[offset].remaining()</tt> bytes of this sequence 71 * are written from buffer <tt>srcs[offset]</tt>, up to the next 72 * <tt>srcs[offset+1].remaining()</tt> bytes are written from buffer 73 * <tt>srcs[offset+1]</tt>, 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 <tt>srcs.length</tt> 96 * 97 * @param length 98 * The maximum number of buffers to be accessed; must be 99 * non-negative and no larger than 100 * <tt>srcs.length</tt> - <tt>offset</tt> 101 * 102 * @return The number of bytes written, possibly zero 103 * 104 * @throws IndexOutOfBoundsException 105 * If the preconditions on the <tt>offset</tt> and <tt>length</tt> 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 <tt>c.write(srcs)</tt> 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} 167