Some channels may not allow more than one read or write to be outstanding + * at any given time. If a thread invokes a read method before a previous read + * operation has completed then a {@link ReadPendingException} will be thrown. + * Similarly, if a write method is invoked before a previous write has completed + * then {@link WritePendingException} is thrown. Whether or not other kinds of + * I/O operations may proceed concurrently with a read operation depends upon + * the type of the channel. + * + *
Note that {@link java.nio.ByteBuffer ByteBuffers} are not safe for use by + * multiple concurrent threads. When a read or write operation is initiated then + * care must be taken to ensure that the buffer is not accessed until the + * operation completes. + * + * @see Channels#newInputStream(AsynchronousByteChannel) + * @see Channels#newOutputStream(AsynchronousByteChannel) + * + * @since 1.7 + */ + +public interface AsynchronousByteChannel + extends AsynchronousChannel +{ + /** + * Reads a sequence of bytes from this channel into the given buffer. + * + *
This method initiates an operation to read a sequence of bytes from + * this channel into the given buffer. The method returns a {@link Future} + * representing the pending result of the operation. The result of the + * operation, obtained by invoking the {@code Future} 's {@link + * Future#get() get} method, is the number of bytes read or {@code -1} if + * all bytes have been read and the channel has reached end-of-stream. + * + *
This method initiates a read operation to read up to r bytes + * from the channel, where r is the number of bytes remaining in the + * buffer, that is, {@code dst.remaining()} at the time that the read is + * attempted. Where r is 0, the read operation completes immediately + * with a result of {@code 0} without initiating an I/O operation. + * + *
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 the read is + * performed. Upon completion the buffer's position will be equal to + * p + n; its limit will not have changed. + * + *
Buffers are not safe for use by multiple concurrent threads so care + * should be taken to not to access the buffer until the operaton has completed. + * + *
This method may be invoked at any time. Some channel types may not + * allow more than one read to be outstanding at any given time. If a thread + * initiates a read operation before a previous read operation has + * completed then a {@link ReadPendingException} will be thrown. + * + *
The handler parameter is used to specify a {@link
+ * CompletionHandler}. When the read operation completes the handler's
+ * {@link CompletionHandler#completed completed} method is executed.
+ *
+ *
+ * @param dst
+ * The buffer into which bytes are to be transferred
+ * @param attachment
+ * The object to attach to the I/O operation; can be {@code null}
+ * @param handler
+ * The completion handler object; can be {@code null}
+ *
+ * @return A Future representing the result of the operation
+ *
+ * @throws IllegalArgumentException
+ * If the buffer is read-only
+ * @throws ReadPendingException
+ * If the channel does not allow more than one read to be outstanding
+ * and a previous read has not completed
+ */
+ Future An invocation of this method of the form c.read(dst)
+ * behaves in exactly the same manner as the invocation
+ * This method initiates an operation to write a sequence of bytes to
+ * this channel from the given buffer. This method returns a {@link
+ * Future} representing the pending result of the operation. The result
+ * of the operation, obtained by invoking the Future's {@link
+ * Future#get() get} method, is the number of bytes written, possibly zero.
+ *
+ * This method initiates a write operation to write up to r bytes
+ * to the channel, where r is the number of bytes remaining in the
+ * buffer, that is, {@code src.remaining()} at the moment the write is
+ * attempted. Where r is 0, the write operation completes immediately
+ * with a result of {@code 0} without initiating an I/O operation.
+ *
+ * Suppose that a byte sequence of length n is written, where
+ * 0 < n <= r.
+ * This byte sequence will be transferred from the buffer starting at index
+ * p, where p is the buffer's position at the moment the
+ * write is performed; the index of the last byte written will be
+ * p + n - 1.
+ * Upon completion the buffer's position will be equal to
+ * p + n; its limit will not have changed.
+ *
+ * Buffers are not safe for use by multiple concurrent threads so care
+ * should be taken to not to access the buffer until the operaton has completed.
+ *
+ * This method may be invoked at any time. Some channel types may not
+ * allow more than one write to be outstanding at any given time. If a thread
+ * initiates a write operation before a previous write operation has
+ * completed then a {@link WritePendingException} will be thrown.
+ *
+ * The handler parameter is used to specify a {@link
+ * CompletionHandler}. When the write operation completes the handler's
+ * {@link CompletionHandler#completed completed} method is executed.
+ *
+ * @param src
+ * The buffer from which bytes are to be retrieved
+ * @param attachment
+ * The object to attach to the I/O operation; can be {@code null}
+ * @param handler
+ * The completion handler object; can be {@code null}
+ *
+ * @return A Future representing the result of the operation
+ *
+ * @throws WritePendingException
+ * If the channel does not allow more than one write to be outstanding
+ * and a previous write has not completed
+ */
+ Future An invocation of this method of the form c.write(src)
+ * behaves in exactly the same manner as the invocation
+ *
+ *
+ * @param dst
+ * The buffer into which bytes are to be transferred
+ *
+ * @return A Future representing the result of the operation
+ *
+ * @throws IllegalArgumentException
+ * If the buffer is read-only
+ * @throws ReadPendingException
+ * If the channel does not allow more than one read to be outstanding
+ * and a previous read has not completed
+ */
+ Future
+ * c.read(dst, null, null);
+ *
+ * @param src
+ * The buffer from which bytes are to be retrieved
+ *
+ * @return A Future representing the result of the operation
+ *
+ * @throws WritePendingException
+ * If the channel does not allow more than one write to be outstanding
+ * and a previous write has not completed
+ */
+ Future
+ * c.write(src, null, null);