Java compact1, compact2, compact3 java.nio.channels Interface AsynchronousByteChannel（JDK8）

Method Detail

• read

  <A> void read(ByteBuffer dst,
                A attachment,
                CompletionHandler<Integer,? super A> handler)

  Reads a sequence of bytes from this channel into the given buffer.

  This method initiates an asynchronous read operation to read a sequence of bytes from this channel into the given buffer. The handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream.

  The read operation may 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 time that the read is attempted. Where r is 0, the read operation completes immediately with a result of 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 access the buffer until the operation 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 ReadPendingException will be thrown.

  Type Parameters:

  A - The type of the attachment

  Parameters:

  dst - The buffer into which bytes are to be transferred

  attachment - The object to attach to the I/O operation; can be null

  handler - The completion handler

  Throws:

  IllegalArgumentException - If the buffer is read-only

  ReadPendingException - If the channel does not allow more than one read to be outstanding and a previous read has not completed

  ShutdownChannelGroupException - If the channel is associated with a group that has terminated

• read

  Future<Integer> read(ByteBuffer dst)

  Reads a sequence of bytes from this channel into the given buffer.

  This method initiates an asynchronous read operation to read a sequence of bytes from this channel into the given buffer. The method behaves in exactly the same manner as the read(ByteBuffer,Object,CompletionHandler) method except that instead of specifying a completion handler, this method returns a Future representing the pending result. The Future's get method returns the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream.

  Parameters:

  dst - The buffer into which bytes are to be transferred

  Returns:

  A Future representing the result of the operation

  Throws:

  IllegalArgumentException - If the buffer is read-only

  ReadPendingException - If the channel does not allow more than one read to be outstanding and a previous read has not completed

• write

  <A> void write(ByteBuffer src,
                 A attachment,
                 CompletionHandler<Integer,? super A> handler)

  Writes a sequence of bytes to this channel from the given buffer.

  This method initiates an asynchronous write operation to write a sequence of bytes to this channel from the given buffer. The handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written.

  The write operation may write up to r bytes to the channel, where r is the number of bytes remaining in the buffer, that is, src.remaining() at the time that the write is attempted. Where r is 0, the write operation completes immediately with a result of 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 access the buffer until the operation 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 WritePendingException will be thrown.

  Type Parameters:

  A - The type of the attachment

  Parameters:

  src - The buffer from which bytes are to be retrieved

  attachment - The object to attach to the I/O operation; can be null

  handler - The completion handler object

  Throws:

  WritePendingException - If the channel does not allow more than one write to be outstanding and a previous write has not completed

  ShutdownChannelGroupException - If the channel is associated with a group that has terminated

• write

  Future<Integer> write(ByteBuffer src)

  Writes a sequence of bytes to this channel from the given buffer.

  This method initiates an asynchronous write operation to write a sequence of bytes to this channel from the given buffer. The method behaves in exactly the same manner as the write(ByteBuffer,Object,CompletionHandler) method except that instead of specifying a completion handler, this method returns a Future representing the pending result. The Future's get method returns the number of bytes written.

  Parameters:

  src - The buffer from which bytes are to be retrieved

  Returns:

  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