Cairngorm初学者入门教程 第六节－－Cairngorm中Command利用Delegate与Service连接

在上一节，我们利用FrontController 去映射 Event与Command

在这一节我们主要针对Command这部分动作做介紹。在RIA应用程序中，不可或缺的部份就是跟后台服务器连接进行数据传递。Command通过Delegate去做Services的部份(包含Remoting,WebServices,…等)

Command: 操作Cairngorm Business以及呼叫Cairngorm Delegates，这些回传所取得的资料Command会再将它更新到Model Locator

Delegate: 由Command所产生，将远程呼叫(RPC:remote procedure calls[HTTP, Web Services, etc])实例化，并将结果传回给Command。

Service:用来定义连接Server端的呼叫(RPC:remote procedure calls[HTTP, Web Services, etc])，来获取远程数据。 
在Delegate中我们会作一个call service的部份，而Services相关的定义与设定，就纪录在Service Locator。

延续上一个项目，我们修改LoginCommand的部份要通过Delegate去做Remoting，呼叫Server端 login function，去数据库查看判断账号密码是否正确。

所以我们先在项目中新增business文件夹。

新增两个文件，一个是Service.mxml组件。用来定义纪录可以使用的Services。

因为组件的类型不是內建，所以先随便选一个再改mxml的內容
这里示范的是使用搭配.NET Remoting的Freeware ” FluorineFx “，可以参考這裡。

代码如下：

<?xml version="1.0" encoding="utf-8"?><cairngorm:ServiceLocator xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:cairngorm="com.adobe.cairngorm.business.*">     <!-- Login Service -->    <mx:RemoteObject     id="Remoting_Services"     source="Remoting.Services"     destination="fluorine"     showBusyCursor="true">        <mx:method name="login" />    </mx:RemoteObject>    </cairngorm:ServiceLocator>

另一个是LoginDelegate.as类，用来连接Service，并将取得的资料回传给Command。

代码如下：

package org.rianotes.CairngormSample.business{     import com.adobe.cairngorm.business.ServiceLocator;      import mx.rpc.IResponder;      import org.rianotes.CairngormSample.vo.User;      public class LoginDelegate {          private var responder:IResponder;        private var service:Object;          public function LoginDelegate(responder:IResponder) {              this.responder = responder;              //透過ServiceLocator取得連接Service的方式            this.service = ServiceLocator.getInstance().getRemoteObject("Remoting_Services");          }          public function login(loginAttempt:User):void{            //這部份要跟Server端Remoting Service 的名字相同傳入值型態也要相同            var call:Object = service.login(loginAttempt);              //處理伺服器的傳回值            call.addResponder( responder );          }      }}

为了传输账号和密码，所以也要针对value object作修改，User------Value object

package org.rianotes.CairngormSample.vo{    //.NET 那邊User.cs的 namespace    [RemoteClass(alias="Remoting.Objects.User")]    public class User    {        public var UserID:String;        public var Password:String;        public var Email:String;          public function User(){          }      }}

然后在LoginCommand中加入Responder要用到的result,fault function
代码如下：

package org.rianotes.CairngormSample.commands{    import com.adobe.cairngorm.commands.ICommand;    import com.adobe.cairngorm.control.CairngormEvent;      import mx.controls.Alert;    import mx.rpc.IResponder;      import org.rianotes.CairngormSample.business.LoginDelegate;    import org.rianotes.CairngormSample.events.LoginEvent;    import org.rianotes.CairngormSample.model.ViewModelLocator;      //加入IResponder 的Interfac才會呼叫result,falut ↓↓↓                public class LoginCommand implements ICommand , IResponder{          public var model:ViewModelLocator = ViewModelLocator.getInstance();          public function LoginCommand(){          }          //ICommand Interface function        public function execute(event:CairngormEvent):void{              var loginEvent:LoginEvent = event as LoginEvent;                  var delegate:LoginDelegate = new LoginDelegate(this);            delegate.login(loginEvent.loginAttempt);          }          //delegate.login 成功取得回傳時做的function        public function result( event :Object):void{            if(event.result == true)            {                model.workflowState = ViewModelLocator.MAIN_SCREEN;            }else            {                mx.controls.Alert.show("請確認帳號密碼是否正確！？");            }        }          //delegate.login 失敗時做的function        public function fault( event :Object):void{            trace("連線錯誤")        }    }}

LoginView.mxml也要做部分修改，代码如下：

<?xml version="1.0" encoding="utf-8"?><mx:VBox xmlns:mx="http://www.adobe.com/2006/mxml" horizontalAlign="right" xmlns:components="org.rianotes.CairngormSample.view.components.*">    <mx:Script>        <![CDATA[            import org.rianotes.CairngormSample.vo.User;            import org.rianotes.CairngormSample.events.LoginEvent;            import org.rianotes.CairngormSample.model.ViewModelLocator;            [Bindable]            private var model:ViewModelLocator = ViewModelLocator.getInstance();             private function login(e:MouseEvent):void{                var user:User = new User();                user.UserID = ti_UserID.text;                user.Password = ti_Password.text;                 var loginEvent:LoginEvent = new LoginEvent(user);                 //發送Login Event                loginEvent.dispatch();                }         ]]>    </mx:Script>    <mx:Form borderStyle="solid" width="100%">        <mx:FormItem label="UserID :" width="100%">            <mx:TextInput id="ti_UserID" width="100%"/>        </mx:FormItem>         <mx:FormItem label="Password: " width="100%">            <mx:TextInput id="ti_Password" width="100%"/>        </mx:FormItem>    </mx:Form>    <mx:Button label="Login" click="login(event)" /></mx:VBox>

最后我们在Main.mxml中加入Service
代码如下：

<?xml version="1.0" encoding="utf-8"?><mx:Application  xmlns:mx="http://www.adobe.com/2006/mxml"  xmlns:view="org.rianotes.CairngormSample.view.*" layout="absolute" xmlns:control="org.rianotes.CairngormSample.control.*" xmlns:business="org.rianotes.CairngormSample.business.*">     <mx:Script>        <![CDATA[            import org.rianotes.CairngormSample.model.ViewModelLocator;            [Bindable]            private var model:ViewModelLocator = ViewModelLocator.getInstance();        ]]>    </mx:Script>     <!--Cairngorm FrontController :讓app中擁有SampleController-->    <control:SampleController id="controller" />     <!--Cairngorm Services-->    <business:Services id="services" />     <mx:ViewStack id="vsMain" width="100%" height="100%"     selectedIndex="{model.workflowState}">           <!--第0個View-->        <view:LoginView />         <!--第1個View-->        <view:MainView />    </mx:ViewStack> </mx:Application>