Java tutorial
/* * Copyright (c) 2000, 2001, 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 write bytes from a sequence of buffers. * * <p> A <i>gathering</i> write operation writes, in a single invocation, a * sequence of bytes from one or more of a given sequence of buffers. * Gathering writes 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>scattering</i> read operations are defined in the {@link * ScatteringByteChannel} interface. </p> * * * @author Mark Reinhold * @author JSR-51 Expert Group * @since 1.4 */ public interface GatheringByteChannel extends WritableByteChannel { /** * Writes a sequence of bytes to this channel from a subsequence of the * given buffers. * * <p> An attempt is made to write up to <i>r</i> bytes to this channel, * where <i>r</i> is the total number of bytes remaining in the specified * subsequence of the given buffer array, that is, * * <blockquote><pre> * srcs[offset].remaining() * + srcs[offset+1].remaining() * + ... + srcs[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 written, where * {@code 0} {@code <=} <i>n</i> {@code <=} <i>r</i>. * Up to the first {@code srcs[offset].remaining()} bytes of this sequence * are written from buffer {@code srcs[offset]}, up to the next * {@code srcs[offset+1].remaining()} bytes are written from buffer * {@code srcs[offset+1]}, and so forth, until the entire byte sequence is * written. As many bytes as possible are written from 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> Unless otherwise specified, a write operation will return only after * writing all of the <i>r</i> requested bytes. Some types of channels, * depending upon their state, may write only some of the bytes or possibly * none at all. A socket channel in non-blocking mode, for example, cannot * write any more bytes than are free in the socket's output buffer. * * <p> This method may be invoked at any time. If another thread has * already initiated a write operation upon this channel, however, then an * invocation of this method will block until the first operation is * complete. </p> * * @param srcs * The buffers from which bytes are to be retrieved * * @param offset * The offset within the buffer array of the first buffer from * which bytes are to be retrieved; must be non-negative and no * larger than {@code srcs.length} * * @param length * The maximum number of buffers to be accessed; must be * non-negative and no larger than * {@code srcs.length} - {@code offset} * * @return The number of bytes written, possibly zero * * @throws IndexOutOfBoundsException * If the preconditions on the {@code offset} and {@code length} * parameters do not hold * * @throws NonWritableChannelException * If this channel was not opened for writing * * @throws ClosedChannelException * If this channel is closed * * @throws AsynchronousCloseException * If another thread closes this channel * while the write operation is in progress * * @throws ClosedByInterruptException * If another thread interrupts the current thread * while the write 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 write(ByteBuffer[] srcs, int offset, int length) throws IOException; /** * Writes a sequence of bytes to this channel from the given buffers. * * <p> An invocation of this method of the form {@code c.write(srcs)} * behaves in exactly the same manner as the invocation * * <blockquote><pre> * c.write(srcs, 0, srcs.length);</pre></blockquote> * * @param srcs * The buffers from which bytes are to be retrieved * * @return The number of bytes written, possibly zero * * @throws NonWritableChannelException * If this channel was not opened for writing * * @throws ClosedChannelException * If this channel is closed * * @throws AsynchronousCloseException * If another thread closes this channel * while the write operation is in progress * * @throws ClosedByInterruptException * If another thread interrupts the current thread * while the write 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 write(ByteBuffer[] srcs) throws IOException; }