理解消息订阅发布机制1-----聊天室改写

  原始的例子是和后台结合写的，下面的是分开写的，其实也没有改什么，主要是熟悉下这种机制，以后被遗忘之神光临了，好有个线索找回来 ，呵呵。

------》前台

<?xml version="1.0" encoding="utf-8"?>
<mx:Panel xmlns:mx="http://www.adobe.com/2006/mxml" width="100%" height="100%"
	creationComplete="initComp()">

	<mx:Script>
		<![CDATA[
			import mx.messaging.channels.StreamingAMFChannel;
			import mx.messaging.ChannelSet;
			import mx.messaging.channels.AMFChannel;
			import mx.messaging.events.MessageEvent;
			import mx.messaging.messages.AsyncMessage;
			import mx.messaging.messages.IMessage;


			private function initComp():void
			{
				var myStreamingAMF:AMFChannel = new StreamingAMFChannel("my-streaming-amf", "http://localhost:8400/samples/messagebroker/streamingamf");
				var myPollingAMF:AMFChannel = new AMFChannel("my-polling-amf", "http://localhost:8400/samples/messagebroker/amfpolling");
				myPollingAMF.pollingEnabled = true;
				myPollingAMF.pollingInterval = 2000;
				var channelSet:ChannelSet = new ChannelSet();
				channelSet.addChannel(myStreamingAMF);
				channelSet.addChannel(myPollingAMF);
				consumer.channelSet = channelSet;				
				producer.channelSet = channelSet;
			}

			public function set room(name:String):void
			{
				if (!name) return;
				
				if (consumer && consumer.subscribed) 
				{
					log.text += "Leaving room " + consumer.destination + "\n";	
					consumer.unsubscribe();
				}
				consumer.destination = name;
				producer.destination = name;
				consumer.subscribe();
				log.text += "Entering room " + name + "\n";	
			}
			
			private function send():void
			{
				var message:IMessage = new AsyncMessage();
				message.body = msg.text;
				producer.send(message);
				msg.text = "";
			}
							
			private function messageHandler(event:MessageEvent):void
			{
				log.text += event.message.body + "\n";	
			}
		]]>
	</mx:Script>

	<mx:Producer id="producer"/>
	<mx:Consumer id="consumer" message="messageHandler(event)"/>

	<mx:TextArea id="log" width="100%" height="100%"/>
	
	<mx:ControlBar>
		<mx:TextInput id="msg" width="100%" enter="send()" enabled="{consumer.subscribed}"/>
		<mx:Button label="Send" click="send()" enabled="{consumer.subscribed}"/>
	</mx:ControlBar>
	
</mx:Panel>

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*" layout="horizontal"
	creationComplete="srv.getRoomList()">

	<mx:RemoteObject id="srv" destination="chat-room-service" endpoint="http://localhost:8400/samples/messagebroker/amf"
		fault="Alert.show(event.fault.rootCause.message, 'Error')"/>

	<mx:Panel title="Room List" width="100%" height="100%" paddingTop="4" paddingLeft="4" paddingBottom="4" paddingRight="4">

		<mx:Label text="Select a room and start chatting in the right panel:"/>
		<mx:List id="list" dataProvider="{srv.getRoomList.lastResult}" width="100%" height="100%"/>

		<mx:ControlBar>
			<mx:VBox width="100%">
				<mx:Button label="Refresh" click="srv.getRoomList()"/>
				<mx:Spacer height="2"/>
				<mx:HRule width="100%" height="1"/>
				<mx:Label text="Create a room:"/>
				<mx:HBox>
					<mx:TextInput id="room"/>
					<mx:Button label="Create" click="srv.createRoom(room.text)" enabled="{room.text.length>0}"/>
				</mx:HBox>
			</mx:VBox>
		</mx:ControlBar>		
		
	</mx:Panel>
	
	<ChatPanel title="Chat" room="{list.selectedItem}"/>

	<mx:Script>
		<![CDATA[
			import mx.controls.Alert;
		]]>
	</mx:Script>
	
</mx:Application>

------》后台

package com.xj.manager;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.springframework.stereotype.Service;

import flex.messaging.MessageBroker;
import flex.messaging.MessageDestination;
//import flex.messaging.config.ServerSettings;
import flex.messaging.services.MessageService;

/**
 * Simplistic implementation of a chat room management service. Clients can add rooms,
 * and obtain a list of rooms. The interesting part of this example is the "on-the-fly" 
 * creation of a message destination. The same technique can be used to create DataService
 * and Remoting destinations. 
 */
@Service
public class ChatRoomService {

	private List rooms;
	
	public ChatRoomService()
	{
		rooms = Collections.synchronizedList(new ArrayList());
	}

	public List getRoomList()
	{
		return rooms;
	}
	
	public void createRoom(String id) {

		if (roomExists(id))
		{
			throw new RuntimeException("Room already exists");
		}
		
		// Create a new Message destination dynamically
		String serviceId = "message-service";
		MessageBroker broker = MessageBroker.getMessageBroker(null);
		MessageService service = (MessageService) broker.getService(serviceId);
		MessageDestination destination = (MessageDestination) service.createDestination(id);

		if (service.isStarted())
		{
			destination.start();
		}

		rooms.add(id);
		
	}
	
	public boolean roomExists(String id)
	{
		int size = rooms.size();
		for (int i=0; i<size; i++)
		{
			if ( ((String)rooms.get(i)).equals(id) ) 
			{
				return true;
			}
		}
		return false;
	}
}