Cairngorm入门的例子

本文来自：http://www.cnblogs.com/zhainanJohnny/archive/2010/11/28/1890356.html

上一篇介绍了一下Cairngorm的基本组成，下面我给大家展示一个简单的例子。

　　我们按一个完整的Cairngorm流程来介绍这个例子。这个例子很简单，一个按钮和一个标签，当按钮点下之后标签上的数字开始递增。首先，我们需要一个页面，也就是Cairngorm中的View部分：

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<?xml version="1.0" encoding="utf-8"?> 

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<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 

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               xmlns:s="library://ns.adobe.com/flex/spark" 

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               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" 

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               <SPAN style="COLOR: #ff0000">xmlns:model="model.*" xmlns:control="control.*" xmlns:business="business.*"</SPAN> 

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               creationComplete="application1_creationCompleteHandler(event)"> 

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    <fx:Script> 

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        <![CDATA[ 

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            import com.adobe.cairngorm.control.CairngormEventDispatcher;         

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            import control.CountEvent; 

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            import control.MyFrontControl; 

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            import flash.utils.setTimeout; 

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            import model.MyModelLocator; 

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            import mx.events.FlexEvent; 

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            import vo.Num; 

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            private function loggingHandler(evt:MouseEvent):void 

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            { 

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                var num:Num = new Num(); 

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                num.startNum = MyModelLocator.getInstance().count; 

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                var countEvent:CountEvent = new CountEvent(num); 

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                <SPAN style="COLOR: #ff0000">CairngormEventDispatcher.getInstance().dispatchEvent(countEvent);</SPAN> 

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            } 

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            protected function application1_creationCompleteHandler(event:FlexEvent):void 

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            { 

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                lable.text = "0"; 

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            } 

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        ]]> 

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    </fx:Script> 

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    <SPAN style="COLOR: #ff0000"><fx:Declarations> 

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        <control:MyFrontControl/> 

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        <business:MyServiceLocator/> 

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    </fx:Declarations></SPAN> 

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    <s:Label id="lable" x="430" y="158" width="66" height="22" text="{<SPAN style="COLOR: #ff0000">MyModelLocator.getInstance().count</SPAN>}"/> 

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    <s:Button id="button" x="430" y="201" label="start" width="66" click="loggingHandler(event)"/> 

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</s:Application>

　　当用户点击按钮之后，就会调用loggingHandler函数。这loggingHandler中声明了一个自定义Event——CountEvent。

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package control 

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{ 

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    import com.adobe.cairngorm.control.CairngormEvent; 

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    import vo.Num; 

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    public class CountEvent <SPAN style="COLOR: #ff0000">extends CairngormEvent</SPAN> 

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    { 

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        public var num:Num = new Num(); 

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        public function CountEvent(num:Num) 

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        { 

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            super(MyFrontControl.COUNT_EVENT); 

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            this.num = num; 

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        } 

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    } 

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}

　　CountEvent的构造函数中有一句super(MyFrontControl.COUNT_EVENT)，在上一篇中我们讲到FrontControl的作用是监听所有Event，其中COUNT_EVENT就是我们所定义的Event的type，记住，CairngormEvent也是继承自Event的。当然，COUNT_EVENT不是凭空产生的，是我们在自定义的FrontControl中定义的。自定义的FrontControl代码如下：

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package control 

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{ 

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    import com.adobe.cairngorm.control.FrontController; 

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    import command.CountCommand; 

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    public class MyFrontControl extends FrontController 

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    { 

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        public static var COUNT_EVENT:String = "counting"; 

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        public function MyFrontControl() 

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        { 

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            this.addCommand(COUNT_EVENT,CountCommand); 

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        } 

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    } 

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}

　　FrontControl管理所有的Event，监听它们并且接受处理它们，回想一下Observer Pattern，我们会在把所有的Observer对象存入Subject中，当事件发生之后Subject会在其内部的表中查找相应的Observer然后调用它们的notify方法。你可以用相同的方法去理解FrontControl的机制，试想，如果我有两个Event，那么FrontControl就应该这样写了：

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package control 

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{ 

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    import com.adobe.cairngorm.control.FrontController; 

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    import command.CountCommand; 

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    import command.CountCommand2; 

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    public class MyFrontControl extends FrontController 

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    { 

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        public static var COUNT_EVENT:String = "counting"; 

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        public static var COUNT_EVENT2:String = "counting2"; 

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        public function MyFrontControl() 

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        { 

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            this.addCommand(COUNT_EVENT,CountCommand); 

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            this.addCommand(COUNT_EVENT2,CountCommand2); 

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        } 

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    } 

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}

　　FrontControl相当于一个Subject的实例，它把所有需要监听的Event和其对应的Command名称加入到内部的列表，并且对所有的Event进行监听，当接受的Event之后它就会在内部列表中查找这个Event然后调用相应的Command类的execute()方法。

　　现在我们就可以很好地理解CairngormEventDispatcher.getInstance().dispatchEvent(countEvent)这句话了，Event被发送之后FrontControl处理之，现在我们来看FrontControl调用的Command是什么样的。

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package command 

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{ 

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    import business.CountDelegate; 

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    import com.adobe.cairngorm.commands.ICommand; 

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    import com.adobe.cairngorm.control.CairngormEvent; 

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    import control.CountEvent; 

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    import model.MyModelLocator; 

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    import mx.rpc.IResponder; 

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    import mx.rpc.events.ResultEvent;    

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    import vo.Num; 

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    public class CountCommand <SPAN style="COLOR: #ff0000">implements ICommand, IResponder</SPAN> 

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    {        

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        public function CountCommand(){ 

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        }    

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        public function <SPAN style="COLOR: #ff0000">execute</SPAN>(event:CairngormEvent):void 

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        { 

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            <SPAN style="COLOR: #ff0000">var delegate:CountDelegate = new CountDelegate(this);</SPAN> 

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            var countEvent:CountEvent = CountEvent(event); 

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            delegate.count(countEvent.num); 

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        }        

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        public function <SPAN style="COLOR: #ff0000">result</SPAN>(data:Object):void 

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        { 

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            var result:Num = data as Num; 

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            MyModelLocator.getInstance().num = result; 

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            MyModelLocator.getInstance().count = result.startNum; 

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        }        

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        public function <SPAN style="COLOR: #ff0000">fault</SPAN>(info:Object):void 

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        { 

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        }    

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    } 

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}

　　我们看到了execute()方法，其实这个方法在接口ICommand中定义。在execute()方法中，Delegate被声明，并且相应的方法被调用。result()方法同样需引起注意，因为它决定了Delegate调用远程服务之后如何处理结果。记住，result()方法是在Delegate中调用的。fault()方法和result()一样，它们都在接口IResponder中定义。

　　我们接着说自定义的Delegate

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package business 

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{ 

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    import com.adobe.cairngorm.business.ServiceLocator; 

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    import flash.utils.clearTimeout; 

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    import flash.utils.setTimeout;   

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    import mx.rpc.IResponder; 

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    import mx.rpc.events.ResultEvent; 

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    import mx.rpc.remoting.RemoteObject; 

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    import vo.Num; 

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    public class CountDelegate 

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    { 

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        private var responder:IResponder; 

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        private var counter:int; 

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        private var remoteObject:RemoteObject;       

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        public function CountDelegate(responder:IResponder) 

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        { 

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            this.responder = responder; 

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        } 

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        public function count(num:Num):void 

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        { 

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            counter = num.startNum; 

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            <SPAN style="COLOR: #ff0000">remoteObject = ServiceLocator.getInstance().getRemoteObject("counting");    

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            remoteObject.addEventListener(ResultEvent.RESULT,OnResult);</SPAN> 

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            counting(); 

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        }    

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        private function counting():void 

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        { 

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            remoteObject.getOperation("count").send(counter); 

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            flash.utils.setTimeout(counting, 1000);  

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        }    

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        private function OnResult(evt:ResultEvent):void 

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        { 

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            var result:Num = new Num(); 

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            counter = evt.result as int; 

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            result.startNum = counter; 

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            <SPAN style="COLOR: #ff0000">responder.result(result);</SPAN> 

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        }            

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    } 

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}

　　这里我们以一个RemoteObject远程调用为例，首先，我们调用的远程服务在ServiceLocator中定义，可以通过remoteObject = ServiceLocator.getInstance().getRemoteObject("counting")来制定这个远程对象，"counting"是在ServiceLocator中定义的RemoteObject id(当然这个ServiceLocator也是我们自定义的，Cairngorm提供的ServiceLocator是一个单例模式的对象)。然后我们为这个远程对象添加ResultEvent的监听器。当我们收到远程调用的结果时，我们调用responder.result()执行在Command中实现的结果处理方法。

　　下面是我们自定义的ServiceLocator：

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<?xml version="1.0" encoding="utf-8"?> 

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<cairngorm:ServiceLocator xmlns:fx="http://ns.adobe.com/mxml/2009" 

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         xmlns:s="library://ns.adobe.com/flex/spark" 

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         xmlns:mx="library://ns.adobe.com/flex/mx"

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         xmlns:cairngorm="com.adobe.cairngorm.business.*"> 

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    <fx:Declarations> 

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        <s:RemoteObject id="counting" destination="countingService"/> 

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    </fx:Declarations>     

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</cairngorm:ServiceLocator>

　　RemoteObject和Blazeds的配置就不解释了，再附上我们自定义的VO和JAVA服务端代码就完整了。

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package vo 

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{ 

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    import com.adobe.cairngorm.vo.IValueObject; 

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    public class Num implements IValueObject 

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    { 

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        public var startNum:int; 

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    } 

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}

　　JAVA服务端代码　

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package cairngorm; 

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public class CountingService { 

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    public CountingService(){} 

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    public int count(int num){ 

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        return ++num; 

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    } 

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}

posted on 2011-10-21 09:31 夏麦宜阅读(398) 评论(0) 收藏举报