Nonblocking I/O - Java Network Programming - page 368

client . write ( output );
}
} catch ( IOException ex ) {
key . cancel ();
try {
key . channel (). close ();
}
catch ( IOException cex ) {}
}
}
}
}
}
View Buffers
If you know the ByteBuffer read from a SocketChannel contains nothing but elements
of one particular primitive data type, it may be worthwhile to create a view buffer . This
is a new Buffer object of appropriate type (e.g., DoubleBuffer , IntBuffer , etc.), that
draws its data from an underlying ByteBuffer beginning with the current position.
Changes to the view buffer are reflected in the underlying buffer and vice versa. How‐
ever, each buffer has its own independent limit, capacity, mark, and position. View
buffers are created with one of these six methods in ByteBuffer :
public abstract ShortBuffer asShortBuffer ()
public abstract CharBuffer asCharBuffer ()
public abstract IntBuffer asIntBuffer ()
public abstract LongBuffer asLongBuffer ()
public abstract FloatBuffer asFloatBuffer ()
public abstract DoubleBuffer asDoubleBuffer ()
For example, consider a client for the Intgen protocol. This protocol is only going to
read int s, so it may be helpful to use an IntBuffer rather than a ByteBuffer .
Example 11-4 demonstrates. For variety, this client is synchronous and blocking, but it
still uses channels and buffers.
Example 11-4. Intgen client
import java.nio.* ;
import java.nio.channels.* ;
import java.net.* ;
import java.io.IOException ;
public class IntgenClient {
public static int DEFAULT_PORT = 1919 ;
public static void main ( String [] args ) {
if ( args . length == 0 ) {