UDP - Java Network Programming - page 431

private volatile boolean stopped = false ;
ReceiverThread ( DatagramSocket socket ) {
this . socket = socket ;
}
public void halt () {
this . stopped = true ;
}
@Override
public void run () {
byte [] buffer = new byte [ 65507 ];
while ( true ) {
if ( stopped ) return ;
DatagramPacket dp = new DatagramPacket ( buffer , buffer . length );
try {
socket . receive ( dp );
String s = new String ( dp . getData (), 0 , dp . getLength (), "UTF-8" );
System . out . println ( s );
Thread . yield ();
} catch ( IOException ex ) {
System . err . println ( ex );
}
}
}
}
You can run the echo client on one machine and connect to the echo server on a second
machine to verify that the network is functioning properly between them.
DatagramChannel
The DatagramChannel class is used for nonblocking UDP applications, in the same way
as SocketChannel and ServerSocketChannel are used for nonblocking TCP applica‐
tions. Like SocketChannel and ServerSocketChannel , DatagramChannel is a subclass
of SelectableChannel that can be registered with a Selector . This is useful in servers
where one thread can manage communications with multiple clients. However, UDP is
by its nature much more asynchronous than TCP so the net effect is smaller. In UDP, a
single datagram socket can process requests from multiple clients for both input and
output. What the DatagramChannel class adds is the ability to do this in a nonblocking
fashion, so methods return quickly if the network isn't immediately ready to receive or
send data.
Using DatagramChannel
DatagramChannel is a near-complete alternate API for UDP. In Java 6 and earlier, you
still need to use the DatagramSocket class to bind a channel to a port. However, you do