simplemulticastserver.java

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

package net.sf.dz.pnp.custom;

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.freehold.jukebox.logger.LogChannel;
import net.sf.dz.pnp.MulticastServer;
import net.sf.dz.util.MessageDigestFactory;

/**
 * @author Copyright &copy; <a href="mailto:[e-mail]">Vadim Tkachenko</a> 2004
 * @version $Id: SimpleMulticastServer.java,v 1.2 2004/06/28 20:35:49 vtt Exp $
 */
public class SimpleMulticastServer extends MulticastServer {

    public static final LogChannel CH_SMS = new LogChannel("SimpleMulticastServer");
    
    private MulticastSocket socket;
    private InetAddress group;

    protected void startup() throws Throwable {
    
        group = InetAddress.getByName("239.192.0.1");
        
        // Let's check if the address has proper scope. Since there are many
        // checks to be done, let's make them all, collect the results and
        // report them all at once.
        
        List error = new LinkedList();
        
        if ( !group.isMulticastAddress() ) {
        
            error.add("Not a multicast address");
        }
        
        if ( !group.isMCSiteLocal() ) {
        
            error.add("Not a site local address");
        }
        
        if ( !group.isMCOrgLocal() ) {
        
            error.add("Not an organization local address");
        }
        
        if ( !error.isEmpty() ) {
        
            complain(LOG_WARNING, CH_SMS, "Problems reported for " + group + " (total of " + error.size() + "), code may not work as intended:");
            
            for ( Iterator i = error.iterator(); i.hasNext(); ) {
            
                complain(LOG_WARNING, CH_SMS, i.next());
            }
        }
        
        socket = new MulticastSocket(5001);
        
        // The multicast scope is "site"
        
        socket.setTimeToLive(15);
        socket.joinGroup(group);
        
        complain(LOG_INFO, CH_SMS, "Announcing on " + group + ":5001");
    }
    
    protected void shutdown(Throwable cause) throws Throwable {
    
        socket.leaveGroup(group);
    }
    
    protected void announce() throws Throwable {
    
        String payload = getMessage();
        
        if ( payload == null ) {
        
            // This shouldn't have happened, but anyway...
            
            return;
        }
        
        String md = new MessageDigestFactory().getSHA(payload);
        String message = "SHA{" + md + "} " + payload;
        
        byte data[] = message.getBytes();
        DatagramPacket packet = new DatagramPacket(data, message.length(), group, 5001);
        
        socket.send(packet);
    }
}