int port = DEFAULT_PORT;
try {
port = Integer.parseInt(args[1]);
}
catch (Exception ex) {
}
SocketAddress remote;
try {
remote = new InetSocketAddress(args[0], port);
}
catch (Exception ex) {
System.err.println("Usage: java UDPEchoClientWithChannels host [port]");
return;
}
try {
DatagramChannel channel = DatagramChannel.open();
channel.configureBlocking(false);
channel.connect(remote);
Selector selector = Selector.open();
channel.register(selector, SelectionKey.OP_READ | SelectionKey.OP_WRITE);
ByteBuffer buffer = ByteBuffer.allocate(4);
int n = 0;
int numbersRead = 0;
while (true) {
// wait one minute for a connection
selector.select(60000);
Set readyKeys = selector.selectedKeys();
if (readyKeys.isEmpty() && n == LIMIT) {
// All packets have been written and it doesn't look like any
// more are will arrive from the network
break;
}
else {
Iterator iterator = readyKeys.iterator();
while (iterator.hasNext()) {
SelectionKey key = (SelectionKey) iterator.next();
iterator.remove();
if (key.isReadable()) {
buffer.clear();
channel.read(buffer);
buffer.flip();
int echo = buffer.getInt();
System.out.println("Read: " + echo);
numbersRead++;
}
if (key.isWritable()) {
buffer.clear();
buffer.putInt(n);
buffer.flip();
channel.write(buffer);
System.out.println("Wrote: " + n);
n++;
if (n == LIMIT) {
// All packets have been written; switch to read-only mode
key.interestOps(SelectionKey.OP_READ);
} // end if
} // end while
} // end else
} // end while
} // end while
System.out.println("Echoed " + numbersRead + " out of " + LIMIT + " sent");
System.out.println("Success rate: " + 100.0 * numbersRead / LIMIT + "%");
} // end try
catch (IOException ex) {
System.err.println(ex);
} // end catch
