/*
* @(#)ReadableByteChannel.java 1.17 05/11/17
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.nio.channels;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* A channel that can read bytes.
*
* <p> Only one read operation upon a readable channel may be in progress at
* any given time. If one thread initiates a read operation upon a channel
* then any other thread that attempts to initiate another read operation will
* block until the first operation is complete. Whether or not other kinds of
* I/O operations may proceed concurrently with a read operation depends upon
* the type of the channel. </p>
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @version 1.17, 05/11/17
* @since 1.4
*/
public interface ReadableByteChannel extends Channel {
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* <p> An attempt is made to read up to <i>r</i> bytes from the channel,
* where <i>r</i> is the number of bytes remaining in the buffer, that is,
* <tt>dst.remaining()</tt>, at the moment this method is invoked.
*
* <p> Suppose that a byte sequence of length <i>n</i> is read, where
* <tt>0</tt> <tt><=</tt> <i>n</i> <tt><=</tt> <i>r</i>.
* This byte sequence will be transferred into the buffer so that the first
* byte in the sequence is at index <i>p</i> and the last byte is at index
* <i>p</i> <tt>+</tt> <i>n</i> <tt>-</tt> <tt>1</tt>,
* where <i>p</i> is the buffer's position at the moment this method is
* invoked. Upon return the buffer's position will be equal to
* <i>p</i> <tt>+</tt> <i>n</i>; its limit will not have changed.
*
* <p> A read operation might not fill the buffer, and in fact it might not
* read any bytes at all. Whether or not it does so depends upon the
* nature and state of the channel. A socket channel in non-blocking mode,
* for example, cannot read any more bytes than are immediately available
* from the socket's input buffer; similarly, a file channel cannot read
* any more bytes than remain in the file. It is guaranteed, however, that
* if a channel is in blocking mode and there is at least one byte
* remaining in the buffer then this method will block until at least one
* byte is read.
*
* <p> This method may be invoked at any time. If another thread has
* already initiated a read operation upon this channel, however, then an
* invocation of this method will block until the first operation is
* complete. </p>
*
* @param dst
* The buffer into which bytes are to be transferred
*
* @return The number of bytes read, possibly zero, or <tt>-1</tt> if the
* channel has reached end-of-stream
*
* @throws NonReadableChannelException
* If this channel was not opened for reading
*
* @throws ClosedChannelException
* If this channel is closed
*
* @throws AsynchronousCloseException
* If another thread closes this channel
* while the read operation is in progress
*
* @throws ClosedByInterruptException
* If another thread interrupts the current thread
* while the read 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 int read(ByteBuffer dst) throws IOException;
}