有很多类似股票、外汇、期货等实时行情这种应用，客户端需要显示行情牌价等信息。
目前的作法是：客户端定时向服务器请求，无论数据是否有更新，都把数据发到客户端。
我们这里讲的一种技术不同以上这个做法，我们是采用服务器向客户端推的这种方式，该方式的好处不言自明。blazeds中有一个名为：StreamingAMFChannel 的通道，我们就是采用它来实现向客户端推这个功能。
环境准备：
我采用eclipse（wtp）+ flex3 build 的软件环境。软件安装我这里就不说明了。blazeds我采用的是blazeds_bin_3-0-0-544，其实你只要下载blazeds.war文件即可。
操作步骤：
1 、切换至flex development视图模式下，点右键新建一个Flex Project。
如我的项目名为：flex-blazeds
切换至“java开发视图”，新建名为：cn.bestwiz.design.tc 的包，在该包中，新建名为Tick.java的类，内容如下：
package cn.bestwiz.design.tc;import java.math.BigDecimal;import java.util.Date;public class Tick { private BigDecimal askPrice; private BigDecimal bidPrice; private BigDecimal midPrice; private Date tickTime; private String seqno; public String getSeqno() { return seqno; } public void setSeqno(String seqno) { this.seqno = seqno; } public BigDecimal getAskPrice() { return askPrice; } public void setAskPrice(BigDecimal askPrice) { this.askPrice = askPrice; } public BigDecimal getBidPrice() { return bidPrice; } public void setBidPrice(BigDecimal bidPrice) { this.bidPrice = bidPrice; } public BigDecimal getMidPrice() { return midPrice; } public void setMidPrice(BigDecimal midPrice) { this.midPrice = midPrice; } public Date getTickTime() { return tickTime; } public void setTickTime(Date tickTime) { this.tickTime = tickTime; }}
接下来，再新建一名为：cn.bestwiz.design.tc.servlet 的包，再切换至“j2ee视图”，在该视图模式下，新建一名为“TickCacheServlet.java”的Servlet.
点击“Finish”完成即可。
package cn.bestwiz.design.tc.servlet;import java.io.IOException;import java.math.BigDecimal;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.bestwiz.design.tc.Tick;import flex.messaging.MessageBroker;import flex.messaging.messages.AsyncMessage;import flex.messaging.util.UUIDUtils;public class TickCacheServlet extends HttpServlet { private static FeedThread thread; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { String cmd = req.getParameter("cmd"); if (cmd.equals("start")) { start(); } if (cmd.equals("stop")) { stop(); } } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // TODO Auto-generated method stub super.doGet(req, resp); } @Override public void destroy() { // TODO Auto-generated method stub super.destroy(); } @Override public void init() throws ServletException { // TODO Auto-generated method stub super.init(); } public void start() { if (thread == null) { thread = new FeedThread(); thread.start(); } System.out.println("start!!"); } public void stop() { thread.running = false; thread = null; } public static class FeedThread extends Thread { public boolean running = true; public void run() { MessageBroker msgBroker = MessageBroker.getMessageBroker(null); String clientID = UUIDUtils.createUUID(); int i = 0; while (running) { Tick tick = new Tick(); tick.setAskPrice(new BigDecimal("100")); tick.setBidPrice(new BigDecimal("100")); tick.setMidPrice(new BigDecimal("100")); tick.setTickTime(new Date()); tick.setSeqno(String.valueOf(i)); System.out.println(i); AsyncMessage msg = new AsyncMessage(); msg.setDestination("tick-data-feed"); msg.setHeader("DSSubtopic", "tick"); msg.setClientId(clientID); msg.setMessageId(UUIDUtils.createUUID()); msg.setTimestamp(System.currentTimeMillis()); msg.setBody(tick); msgBroker.routeMessageToService(msg, null); i++; try { Thread.sleep(20); } catch (InterruptedException e) { } } } }}
下一步加入flex配置文件。
flex的配置文件默认有四个，文件目录在WebContent/WEB-INF/flex目录下。
messaging-config.xml
proxy-config.xml
remoting-config.xml
services-config.xml
其实，这中间用的是一个，就是services-config.xml，只是在services-config.xml中，包含其它三个。
在services-config.xml文件中，加入如下：
<channel-definition id="my-streaming-amf" class="mx.messaging.channels.StreamingAMFChannel"> <endpoint url="http://{server.name}:{server.port}/{context.root}/messagebroker/streamingamf" class="flex.messaging.endpoints.StreamingAMFEndpoint"/> <properties> <idle-timeout-minutes>0</idle-timeout-minutes> <max-streaming-clients>10</max-streaming-clients> <server-to-client-heartbeat-millis>5000</server-to-client-heartbeat-millis> <user-agent-settings> <user-agent match-on="MSIE" kickstart-bytes="2048" max-streaming-connections-per-session="1"/> <user-agent match-on="Firefox" kickstart-bytes="2048" max-streaming-connections-per-session="1"/> </user-agent-settings> </properties> </channel-definition>
messaging-config.xml文件中，加入如下：
<destination id="tick-data-feed"> <properties> <server> <allow-subtopics>true</allow-subtopics> <subtopic-separator>.</subtopic-separator> </server> </properties> <channels> <channel ref="my-polling-amf" /> <channel ref="my-streaming-amf" /> </channels> </destination>
再切换至flex 开发视图，新建一名为：Tick.as的ActionScript文件。
点击“Finish”按纽。
package { [RemoteClass(alias="cn.bestwiz.design.tc.Tick")] [Bindable] public class Tick { public var askPrice:Number; public var bidPrice:Number; public var midPrice:Number; public var tickTime:Date;; public var seqno:String; } }
再在main.mxml文件中，加入如下代码：<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" viewSourceURL="srcview/index.html" height="378" width="426"> <mx:Script> <![CDATA[ import mx.controls.Alert; import mx.rpc.events.ResultEvent; import mx.messaging.Consumer; import mx.messaging.Channel; import mx.messaging.ChannelSet; import mx.messaging.events.MessageEvent; [Bindable] public var tick:Tick; public function submsg():void { Alert.show("click start"); var consumer:Consumer = new Consumer(); consumer.destination = "tick-data-feed"; consumer.subtopic = "tick"; consumer.channelSet = new ChannelSet(["my-streaming-amf"]); consumer.addEventListener(MessageEvent.MESSAGE, messageHandler); consumer.subscribe(); Alert.show("click end"); } private function messageHandler(event:MessageEvent):void { var tick:Tick = event.message.body as Tick; txtTick.text = tick.seqno; } ]]> </mx:Script> <mx:Panel x="32" y="43" width="362" height="302" layout="absolute" title="Watch Tick"> <mx:Label x="72" y="43" text="Label" id="txtTick"/> <mx:Button x="132" y="41" label="Button" click="submsg(); "/> </mx:Panel></mx:Application>
OK,至此，我们的代码全部结束了。
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