udpserviceimpl.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.net.SocketException;
import java.util.Hashtable;

import org.butor.config.Config;
import org.butor.config.lowlevel.IProperties;
import org.butor.fwService.FwServiceImpl;
import org.butor.log.Log;
import org.butor.net.udp.service.IUDPSocketReceiver;
import org.butor.net.udp.service.UDPSocketReceiver;
import org.butor.resourcePool.threadPoolService.ThreadPool;

/**
 * This service starts a thread that listens on the UDP port
 * specified by udp_port in the main config file.  The datagram's
 * content must be composed of a org.butor.web.listener name followed by a space
 * and the command to pass to that org.butor.web.listener.  The command is then
 * passed to the appropriate org.butor.web.listener.
 *
 * @author Filipe Mateus
 */
public class UDPServiceImpl
	extends FwServiceImpl
	implements IUDPService, IUDPSocketReceiver {
	

	/**
	 * Table of listeners accessible by service id.
	 */
	protected Hashtable f_listeners = new Hashtable();
	protected UDPSocketReceiver f_udpReceiver;
	protected int f_udpPort;
	protected int f_bufferLen;
	
	/* 
	 * 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.
	 */
	protected boolean f_singleListenerMode = false;
	
	/**
	 * Adds the specified udp org.butor.web.listener to receive datagram events.
	 * 
	 * @param org.butor.web.listener Object that will receive datagram events.
	 */
	public void registerUdpMessageListener(IUDPMessageListener listener) {
		String name = listener.getUdpMessageListenerName();

		Log.logStr(
			Log.LOG_LEVEL_LOW,
			this,
			Log.LOG_TYPE_INFO,
			"registerListener()",
			"registering " + name);

		synchronized(f_listeners) {
			if (f_listeners.containsKey(name)) {
				Log.logStr(
					this,
					Log.LOG_TYPE_WARN,
					"registerListener()",
					name + " already registered");
				return;
			}
		
			f_listeners.put(name, listener);
		}
	}
	/**
	 * Remove the specified udp org.butor.web.listener.
	 * 
	 * @param org.butor.web.listener Object that will be unregistered.
	 */
	public void unregisterUdpMessageListener(IUDPMessageListener listener) {
		String name = listener.getUdpMessageListenerName();

		Log.logStr(
			Log.LOG_LEVEL_LOW,
			this,
			Log.LOG_TYPE_INFO,
			"unregisterListener()",
			"registering " + name);

		synchronized(f_listeners) {
			if (!f_listeners.containsKey(name)) {
				Log.logStr(
					this,
					Log.LOG_TYPE_WARN,
					"unregisterListener()",
					name + " was not registered!");
				return;
			}
		
			f_listeners.remove(name);
		}
	}
	/**
	 * Gets the Hashtable containing the list of listeners.
	 * key: Listener name, value: IUDPListener object.
	 */
	public Hashtable getListeners() {
		return f_listeners;
	}
	/**
	 * Get registered org.butor.web.listener.
	 * 
	 * @param name String, org.butor.web.listener name.
	 * 
	 * @return IAdminMessageHandler
	 */
	public IUDPMessageListener getUdpMessageListener(String name) {
		if (name == null) {
			Log.logStr(this, Log.LOG_TYPE_ERROR, "getUdpMessageListener()", 
				"Got null org.butor.web.listener name!");
			return null;
		}
		
		synchronized(f_listeners) {
			return (IUDPMessageListener)f_listeners.get(name);
		}
	}
	/**
	 * 
	 */
	public void init() {
		Log.logStr(this, Log.LOG_TYPE_INFO, "init()", "...");
		
		// get service config.
		IProperties serviceProps = Config.getPropertyList(
			FwServiceImpl.PROPERTY_PREFIX_SERVICE +getServiceName());
	
		if (serviceProps == null) {
			Log.logStr(
				this,
				Log.LOG_TYPE_ERROR,
				"init()",
				"Missing property list [" 
					+ FwServiceImpl.PROPERTY_PREFIX_SERVICE +getServiceName()
					+ "]");
	
			return;
					
		} else {
			f_udpPort = serviceProps.getPropertyInt(UDPService.PROPERTY_LISTEN_PORT, 0);
			f_bufferLen = serviceProps.getPropertyInt(UDPService.PROPERTY_BUFFER_LENGTH, 0);

			/* 
			 * 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.
			 */
			f_singleListenerMode = serviceProps.getPropertyBoolean(UDPService.PROPERTY_SINGLE_LISTENER_MODE, true);
		}
		
		try {
			f_udpReceiver = new UDPSocketReceiver(f_udpPort, f_bufferLen, this);
			
		} catch (SocketException e) {
			Log.logStr(this, Log.LOG_TYPE_ERROR, "init()", 
			"Can't start because of error: " +e.getMessage());
			return;
		}
	}
	/**
	 * 
	 */
	public void isAlive() {
		Log.logStr(Log.LOG_LEVEL_FULL, this, Log.INFO, "isAlive", "I'm alive ...");
	}
	/**
	 * Splits the org.butor.web.listener name from the command and invokes
	 * the appropriate org.butor.web.listener.
	 *
	 * @param command Raw content of the received datagram containing
	 *					the org.butor.web.listener's name followed by the command.
	 */
	public void handleUDPMessage(String udpMessage) {
		UDPMessageDispatcher dispatcher = new UDPMessageDispatcher(udpMessage);
		ThreadPool.run(dispatcher);
	}
	/**
	 * 
	 */
	public void shutdown() {
		unregisterFromService();
		if (f_udpReceiver != null) {
			f_udpReceiver.shutdown();
		}
	}
	/**
	 * Tell if the service is started in single org.butor.web.listener mode.
	 * 
	 * message will be sent to all registered listeners if in single 
	 * org.butor.web.listener mode. If not then message will be send to the 
	 * specified org.butor.web.listener only.
	 *
	 * @return boolean.
	 */
	public boolean isSingleListenerMode() {
		return f_singleListenerMode;
	}
	
	/**
	 * Returns the port number on which datagrams are listened.
	 * 
	 * @return port number
	 */	
	public int getListenPort() {
		return f_udpPort;
	}
}