Reading lots of bytes from a socket channel

Question

Hello,
I have a client/server architecture.
My server writes() to a socketChannel the contents large byteBuffer.
On my client, I read() the socketChannel in to a byteBuffer. However, the data I wrote to the socketChannel is so large that it doesn't all arrive in one read(). I get a byteBuffer, but it isn't complete.
Is there any way to know that there is more data waiting on the socketChannel, as it were? Or do I need to handle this myself by keeping track of the number of incoming bytes?
Cheers!

Answer 1

I was wondering whether Java had any kind of internal way of saying "I've not yet finished writing what I was told to write....there's more data to come".Socket.Channel.write() returns a byte count. If it's less that you expect, the write was incomplete.
I suspect the answer is "no"No, the answer is 'yes', unless you are ignoring the return value.
The canonical way to write a buffer is this:
while (buffer.position() > 0)
  try
    buffer.flip();
    int rc = channel.write(buffer);
    if (rc == 0)
        // Here you must register the channel for OP_WRITE
        // and wait for it to trigger before trying again, not shown.
        key.interestOps(SelectionKey.OP_WRITE);
        break;
  finally
    buffer.compact();
if (buffer.position() == 0)
  // The entire buffer has been written.
  // At this point you deregister the channel for OP_WRITE,
  key.interestOps(0);
  // or more probably re-register for OP_READ.
  key.interestOps(SelectionKey.OP_READ);
}