src.java.nio.channels.ReadableByteChannel Maven / Gradle / Ivy
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* 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.
*
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package java.nio.channels;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* A channel that can read bytes.
*
* 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.
*
*
* @author Mark Reinhold
* @author JSR-51 Expert Group
* @since 1.4
*/
public interface ReadableByteChannel extends Channel {
/**
* Reads a sequence of bytes from this channel into the given buffer.
*
* An attempt is made to read up to r bytes from the channel,
* where r is the number of bytes remaining in the buffer, that is,
* dst.remaining(), at the moment this method is invoked.
*
*
Suppose that a byte sequence of length n is read, where
* 0 <= n <= r.
* This byte sequence will be transferred into the buffer so that the first
* byte in the sequence is at index p and the last byte is at index
* p + n - 1,
* where p is the buffer's position at the moment this method is
* invoked. Upon return the buffer's position will be equal to
* p + n; its limit will not have changed.
*
*
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.
*
*
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.
*
* @param dst
* The buffer into which bytes are to be transferred
*
* @return The number of bytes read, possibly zero, or -1 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;
}