int port;
try {
port = Integer.parseInt(args[0]);
}
catch (Exception ex) {
port = DEFAULT_PORT;
}
System.out.println("Listening for connections on port " + port);
ServerSocketChannel serverChannel;
Selector selector;
try {
serverChannel = ServerSocketChannel.open();
ServerSocket ss = serverChannel.socket();
InetSocketAddress address = new InetSocketAddress(port);
ss.bind(address);
serverChannel.configureBlocking(false);
selector = Selector.open();
serverChannel.register(selector, SelectionKey.OP_ACCEPT);
}
catch (IOException ex) {
ex.printStackTrace();
return;
}
while (true) {
try {
selector.select();
}
catch (IOException ex) {
ex.printStackTrace();
break;
}
Set readyKeys = selector.selectedKeys();
Iterator iterator = readyKeys.iterator();
while (iterator.hasNext()) {
SelectionKey key = (SelectionKey) iterator.next();
iterator.remove();
try {
if (key.isAcceptable()) {
ServerSocketChannel server = (ServerSocketChannel ) key.channel();
SocketChannel client = server.accept();
System.out.println("Accepted connection from " + client);
client.configureBlocking(false);
SelectionKey key2 = client.register(selector, SelectionKey.OP_WRITE);
ByteBuffer output = ByteBuffer.allocate(4);
output.putInt(0);
output.flip();
key2.attach(output);
}
else if (key.isWritable()) {
SocketChannel client = (SocketChannel) key.channel();
ByteBuffer output = (ByteBuffer) key.attachment();
if (! output.hasRemaining()) {
output.rewind();
int value = output.getInt();
output.clear();
output.putInt(value+1);
output.flip();
}
client.write(output);
}
}
catch (IOException ex) {
key.cancel();
try {
key.channel().close();
}
catch (IOException cex) {}
}
}
}
