udpservice.java

一个实用工具类

/*
 * Copyright (C) butor.com. All rights reserved.
 *
 * This software is published under the terms of the GNU Library General
 * Public License (GNU LGPL), a copy of which has been included with this
 * distribution in the LICENSE.txt file. 
 */


package org.butor.net.udp;

import java.util.Hashtable;
import java.util.Vector;

import org.butor.fwService.FwService;
import org.butor.fwService.IFwServiceImpl;
import org.butor.log.Log;
/**
 * 
 *
 * @author Aiman SAWAN
 */
public abstract class UDPService {
	
	public final static String PROPERTY_LISTEN_PORT = "listen_port";
	public final static String PROPERTY_BUFFER_LENGTH = "buffer_length";
	public final static String PROPERTY_SINGLE_LISTENER_MODE = "single_listener_mode";
	
	/**
	 * Config key indicating wether or not to register
	 * itself against the UDP service
	 */
	public static final String PROPERTY_ENABLE_UDP_MESSAGE_CFG = "enable_udp_message";
	/**
	 * By default, register itself against the UDP service
	 */
	public static final boolean PROPERTY_ENABLE_UDP_MESSAGE_CFG_DEF = true;

	/*
	 * will register org.butor.web.listener until an implementation
	 * will be registered. 
	 */
	protected static Vector s_listeners;
	
	protected static FwService fwService = new FwService(UDPService.class);

	public static boolean isImplCompatible(IFwServiceImpl impl) {
		return (impl instanceof IUDPService); 
	}
	public static String getServiceName() {
		return UDPService.class.getName();
	}
	public static void registerImpl(IFwServiceImpl impl) {
		fwService.registerImpl(impl);
		IUDPService uImpl = getImpl("registerImpl()");
		if (null != uImpl) {
			// register waiting liteners if any.
			if (s_listeners != null) {
				for (int i=0; i<s_listeners.size(); i++) {
					uImpl.registerUdpMessageListener((IUDPMessageListener) s_listeners.elementAt(i));
				}
			}
		}
	}
	public static void unregisterImpl(IFwServiceImpl impl) {
		fwService.unregisterImpl(impl);
	}
	protected static IUDPService getImpl(String calledMethod) {
		return (IUDPService)fwService.getImpl(calledMethod);
	}

	/**
	 * Tell if the service is started in single org.butor.web.listener mode.
	 * 
	 * Send message to all registered listeners if not in single 
	 * org.butor.web.listener mode. If in single org.butor.web.listener mode then send message 
	 * to the specified org.butor.web.listener only.
	 *
	 * @return boolean.
	 */
	public static boolean isSingleListenerMode() {
		IUDPService impl = getImpl("isSingleListenerMode()");
		if (null != impl) {
			return impl.isSingleListenerMode();
		}
		return false;
	}
	/**
	 * Register an IUDPListener
	 * 
	 * @param org.butor.web.listener IUDPListener, org.butor.web.listener interested to
	 * 		receive datagram messages.
	 */
	public synchronized static void registerUdpMessageListener(IUDPMessageListener listener) {
		IUDPService impl = getImpl("isSingleListenerMode()");
		if (null != impl) {
			impl.registerUdpMessageListener(listener);
			return;
		}
		Log.logStr(UDPService.class, Log.LOG_TYPE_INFO, "registerUdpMessageListener()",
			"keeping org.butor.web.listener until an implementation register.");
		
		if (s_listeners == null) {
			s_listeners = new Vector();
		}
		s_listeners.addElement(listener);
	}
	/**
	 * unRegister an IUDPListener
	 * 
	 * @param org.butor.web.listener IUDPListener
	 */
	public synchronized static void unregisterUdpMessageListener(IUDPMessageListener listener) {
		IUDPService impl = getImpl("unregisterUdpMessageListener()");
		if (null != impl) {
			impl.unregisterUdpMessageListener(listener);
		}
	}
	/**
	 * Get registered listeners.
	 * 
	 * @return Hashtable
	 */
	public static Hashtable getListeners() {
		IUDPService impl = getImpl("getListeners()");
		if (null != impl) {
			return impl.getListeners();
		}
		return null;
	}
	/**
	 * Get registered org.butor.web.listener.
	 * 
	 * @param name String, org.butor.web.listener name.
	 * 
	 * @return IAdminMessageHandler
	 */
	public static IUDPMessageListener getUdpMessageListener(String name) {
		IUDPService impl = getImpl("getListeners()");
		if (null != impl) {
			return impl.getUdpMessageListener(name);
		}
		return null;
	}
	
	/**
	 * Returns the port number on which datagrams are listened.
	 * 
	 * @return port number
	 */	
	public static int getListenPort() {
		IUDPService impl = getImpl("getListeners()");
		if (null != impl) {
			return impl.getListenPort();
		}
		return -1;
	}
}