multicastclient.java

来自「这是一个以JAVA编写的程序,本人还没有试过,是一个简单的温度控制系统」· Java 代码 · 共 94 行

package net.sf.dz.pnp;

import java.net.SocketException;
import java.util.Iterator;
import java.util.HashSet;
import java.util.Set;

import org.freehold.jukebox.logger.LogChannel;
import org.freehold.jukebox.service.ActiveService;

/**
 * An abstract multicast client.
 *
 * <p>
 *
 * Provides a protocol independent listener abstraction for plug-and-play
 * features.
 *
 * @author Copyright &copy; <a href="mailto:[e-mail]">Vadim Tkachenko</a> 2004
 * @version $Id: MulticastClient.java,v 1.3 2004/07/22 17:53:59 vtt Exp $
 */
abstract public class MulticastClient extends ActiveService {

    public static final LogChannel CH_MC = new LogChannel("MulticastClient");
    
    private Set listenerSet = new HashSet();

    protected void execute() throws Throwable {
    
        while ( isEnabled() ) {
        
            try {
            
                MulticastEvent message = receive();
                
                complain(LOG_DEBUG, CH_MC, "Received announce: " + message);
                
                // VT: FIXME: Provide facilities to broadcast to *our*
                // listeners
                
                synchronized ( this ) {

                    for ( Iterator i = listenerSet.iterator(); i.hasNext(); ) {
                    
                        MulticastEventListener l = (MulticastEventListener)i.next();
                        
                        try {
                        
                            complain(LOG_DEBUG, CH_MC, "Notifying " + l);
                        
                            l.multicastEventReceived(this, message);
                            
                        } catch ( Throwable t ) {
                        
                            complain(LOG_WARNING, CH_MC, "Failed to complete notification on '" + message + "':", t);
                        }
                    }
                }
                
            } catch ( Throwable t ) {
            
                // If we've just been stopped, and no event was received
                // since then, we'll get the "Socket closed" exception. 
                // Ignore it. All others won't be ignored, just because I
                // don't know what they could be.
                
                if ( !isEnabled() ) {
                
                    if ( t instanceof SocketException && "Socket closed".equals(t.getMessage()) ) {
                    
                        // Just return

                        return;
                    }
                }
            
                complain(LOG_WARNING, CH_MC, "Failed to receive", t);
            }
        }
    }
    
    public final synchronized void addListener(MulticastEventListener l) {
    
        listenerSet.add(l);
    }
    
    public final synchronized void removeListener(MulticastEventListener l) {
    
        listenerSet.remove(l);
    }
    
    abstract protected MulticastEvent receive() throws Throwable;
}