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.CairngormSamp
a817
le.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>