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109 lines
3.7 KiB
109 lines
3.7 KiB
/*
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* Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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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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* <tt>dst.remaining()</tt>, 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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* <tt>0</tt> <tt><=</tt> <i>n</i> <tt><=</tt> <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> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>,
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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> <tt>+</tt> <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 <tt>-1</tt> 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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