Sockets for Servers - Java Network Programming - page 300

}
}
} catch ( IOException ex ) {
errorLogger . log ( Level . SEVERE , "Couldn't start server" , ex );
} catch ( RuntimeException ex ) {
errorLogger . log ( Level . SEVERE , "Couldn't start server: " + ex . getMessage (), ex );
}
}
private static class DaytimeTask implements Callable < Void > {
private Socket connection ;
DaytimeTask ( Socket connection ) {
this . connection = connection ;
}
@Override
public Void call () {
try {
Date now = new Date ();
// write the log entry first in case the client disconnects
auditLogger . info ( now + " " + connection . getRemoteSocketAddress ());
Writer out = new OutputStreamWriter ( connection . getOutputStream ());
out . write ( now . toString () + "\r\n" );
out . flush ();
} catch ( IOException ex ) {
// client disconnected; ignore;
} finally {
try {
connection . close ();
} catch ( IOException ex ) {
// ignore;
}
}
return null ;
}
}
}
As well as logging, Example 9-6 has also added catch blocks for RuntimeException that
cover most of the code and all of the network connections. This is strongly advisable in
network servers. The last thing you want is for your entire server to fall down just because
one request went down an unplanned code path and threw an IllegalArgumentExcep
tion . Usually when this happens that request is going to fail, but you can continue
processing other requests. If you're even more careful, you can send the client the ap‐
propriate error response. In HTTP, this would be a 500 internal server error.
Not every exception automatically turns into an error log entry. For example, if a client
disconnects while you're writing the time, that's an IOException . However, it's not a bug