Writes a sequence of bytes to this channel from the given buffer.
An attempt is made to write up to r bytes to 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 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 this
method is invoked; the index of the last byte written will be
p + n - 1.
Upon return the buffer's position will be equal to
p + n; its limit will not have changed.
Unless otherwise specified, a write operation will return only after
writing all of the r requested bytes. Some types of channels,
depending upon their state, may write only some of the bytes or possibly
none at all. A socket channel in non-blocking mode, for example, cannot
write any more bytes than are free in the socket's output buffer.
This method may be invoked at any time. If another thread has
already initiated a write operation upon this channel, however, then an
invocation of this method will block until the first operation is
complete.
