UDP - Java Network Programming - page 426

private final int bufferSize ; // in bytes
private final int port ;
private final Logger logger = Logger . getLogger ( UDPServer . class . getCanonicalName ());
private volatile boolean isShutDown = false ;
public UDPServer ( int port , int bufferSize ) {
this . bufferSize = bufferSize ;
this . port = port ;
}
public UDPServer ( int port ) {
this ( port , 8192 );
}
@Override
public void run () {
byte [] buffer = new byte [ bufferSize ];
try ( DatagramSocket socket = new DatagramSocket ( port )) {
socket . setSoTimeout ( 10000 ); // check every 10 seconds for shutdown
while ( true ) {
if ( isShutDown ) return ;
DatagramPacket incoming = new DatagramPacket ( buffer , buffer . length );
try {
socket . receive ( incoming );
this . respond ( socket , incoming );
} catch ( SocketTimeoutException ex ) {
if ( isShutDown ) return ;
} catch ( IOException ex ) {
logger . log ( Level . WARNING , ex . getMessage (), ex );
}
} // end while
} catch ( SocketException ex ) {
logger . log ( Level . SEVERE , "Could not bind to port: " + port , ex );
}
}
public abstract void respond ( DatagramSocket socket , DatagramPacket request )
throws IOException ;
public void shutDown () {
this . isShutDown = true ;
}
}
The easiest protocol to handle is discard. All that's needed is a main() method that sets
the port and starts the thread. respond() is a do-nothing method. Example 12-10 is a
high-performance UDP discard server that does nothing with incoming packets.