Writes a sequence of bytes to this channel from a subsequence of the
given buffers.
An attempt is made to write up to r bytes to this channel,
where r is the total number of bytes remaining in the specified
subsequence of the given buffer array, that is,
srcs[offset].remaining()
+ srcs[offset+1].remaining()
+ ... + srcs[offset+length-1].remaining()
at the moment that this method is invoked.
Suppose that a byte sequence of length n is written, where
0 <= n <= r.
Up to the first srcs[offset].remaining() bytes of this sequence
are written from buffer srcs[offset], up to the next
srcs[offset+1].remaining() bytes are written from buffer
srcs[offset+1], and so forth, until the entire byte sequence is
written. As many bytes as possible are written from each buffer, hence
the final position of each updated buffer, except the last updated
buffer, is guaranteed to be equal to that buffer's limit.
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.
