109 lines
4.6 KiB
Java
109 lines
4.6 KiB
Java
/*
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* Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.nio.channels;
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import java.io.IOException;
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import java.nio.ByteBuffer;
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/**
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* A channel that can read bytes.
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*
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* <p> Only one read operation upon a readable channel may be in progress at
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* any given time. If one thread initiates a read operation upon a channel
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* then any other thread that attempts to initiate another read operation will
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* block until the first operation is complete. Whether or not other kinds of
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* I/O operations may proceed concurrently with a read operation depends upon
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* the type of the channel. </p>
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*
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*
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* @author Mark Reinhold
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* @author JSR-51 Expert Group
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* @since 1.4
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*/
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public interface ReadableByteChannel extends Channel {
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/**
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* Reads a sequence of bytes from this channel into the given buffer.
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*
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* <p> An attempt is made to read up to <i>r</i> bytes from the channel,
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* where <i>r</i> is the number of bytes remaining in the buffer, that is,
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* {@code dst.remaining()}, at the moment this method is invoked.
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*
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* <p> Suppose that a byte sequence of length <i>n</i> is read, where
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* {@code 0} {@code <=} <i>n</i> {@code <=} <i>r</i>.
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* This byte sequence will be transferred into the buffer so that the first
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* byte in the sequence is at index <i>p</i> and the last byte is at index
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* <i>p</i> {@code +} <i>n</i> {@code -} {@code 1},
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* where <i>p</i> is the buffer's position at the moment this method is
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* invoked. Upon return the buffer's position will be equal to
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* <i>p</i> {@code +} <i>n</i>; its limit will not have changed.
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*
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* <p> A read operation might not fill the buffer, and in fact it might not
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* read any bytes at all. Whether or not it does so depends upon the
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* nature and state of the channel. A socket channel in non-blocking mode,
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* for example, cannot read any more bytes than are immediately available
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* from the socket's input buffer; similarly, a file channel cannot read
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* any more bytes than remain in the file. It is guaranteed, however, that
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* if a channel is in blocking mode and there is at least one byte
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* remaining in the buffer then this method will block until at least one
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* byte is read.
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*
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* <p> This method may be invoked at any time. If another thread has
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* already initiated a read operation upon this channel, however, then an
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* invocation of this method will block until the first operation is
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* complete. </p>
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*
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* @param dst
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* The buffer into which bytes are to be transferred
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*
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* @return The number of bytes read, possibly zero, or {@code -1} if the
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* channel has reached end-of-stream
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*
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* @throws NonReadableChannelException
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* If this channel was not opened for reading
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*
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* @throws ClosedChannelException
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* If this channel is closed
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*
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* @throws AsynchronousCloseException
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* If another thread closes this channel
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* while the read operation is in progress
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*
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* @throws ClosedByInterruptException
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* If another thread interrupts the current thread
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* while the read operation is in progress, thereby
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* closing the channel and setting the current thread's
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* interrupt status
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*
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* @throws IOException
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* If some other I/O error occurs
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*/
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public int read(ByteBuffer dst) throws IOException;
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}
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