simplebroadcastserver.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.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;

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

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

    public static final LogChannel CH_SMS = new LogChannel("SimpleBroadcastServer");
    
    private Set allowedAddresses = new HashSet();
    private int port = 5001;
    
    private DatagramSocket socket;
    private Set addressSet = new HashSet();

    public SimpleBroadcastServer() {
    
        super();
    }

    /**
     * Create an instance.
     *
     * @param allowedAddresses Set of <code>String</code> objects
     * representing internet addresses we're allowed to announce from. If
     * the set is empty, it is considered a wildcard, and all local
     * addresses will be used.
     *
     * @param port Port to send the announce on.
     */
    public SimpleBroadcastServer(Set allowedAddresses, int port) throws UnknownHostException {
    
        super();
        
        if ( allowedAddresses == null ) {
        
            throw new IllegalArgumentException("allowed addresses set can't be null");
        }
        
        for ( Iterator i = allowedAddresses.iterator(); i.hasNext(); ) {
        
            InetAddress addr = InetAddress.getByName(i.next().toString());
            
            // VT: Can't complain here, logger is not yet set
            //complain(LOG_DEBUG, CH_SMS, "Allowed: " + addr);
        
            this.allowedAddresses.add(addr);
        }
        
        this.port = port;
    }

    protected void startup() throws Throwable {
    
        socket = new DatagramSocket();
        socket.setBroadcast(true);
        
        // Compose a broadcast address
        
        // VT: FIXME: Right now, the broadcast address will be a class C
        // broadcast address. Unlikely, but it may happen that the host
        // address is class B or even class A address, in this case this
        // address will not be correct. I guess it would be a good idea to
        // determine the address class and adjust accordingly.
        
        Set localAddresses = HostHelper.getLocalAddresses();
        
        for ( Iterator i = localAddresses.iterator(); i.hasNext(); ) {
        
            InetAddress niAddress = (InetAddress)i.next();
            String hostAddress = niAddress.getHostAddress();
            
            if ( "127.0.0.1".equals(hostAddress) ) {
            
                // Just add it
                
                addressSet.add(niAddress);
            
            } else {
            
                // Let's see first if we're allowed to broadcast on this
                // address
                
                if ( !allowedAddresses.isEmpty() && allowedAddresses.contains(niAddress) ) {
            
                    StringTokenizer st = new StringTokenizer(hostAddress, ".");
                        
                    // VT: FIXME: Damn it, is it 0 or 255? I remember 255,
                    // but why does 0 work???
                    
                    String targetAddress = st.nextToken() + "." + st.nextToken() + "." + st.nextToken() + ".0";
                    
                    niAddress = InetAddress.getByName(targetAddress);

                    addressSet.add(niAddress);
                }
            }
        }
        
        // VT: FIXME: Right now, only the last address found will be used
        
        complain(LOG_INFO, CH_SMS, "Announcing on " + addressSet + ":" + port);
    }
    
    protected void shutdown(Throwable cause) throws Throwable {
    
        socket.close();
    }
    
    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();
        
        for ( Iterator i = addressSet.iterator(); i.hasNext(); ) {
        
            InetAddress address = (InetAddress)i.next();
            DatagramPacket packet = new DatagramPacket(data, message.length(), address, port);
            
            socket.send(packet);
        }
    }
}