apache-flex - 使 cairngorm 命令始终同步工作

Question

我看到了异步命令的好处（等待服务器响应......），但在我的 flex 应用程序中，它给我带来的问题比任何事情都多。这就是我想要的：

每个命令仅在前一个返回后执行（结果或故障函数）

而且我想尽可能轻松地做到这一点..顺便说一下，在执行长命令时，GUI必须变得无响应（可能是等待消息）（我可以在执行函数中显示等待消息并将其删除）故障或结果函数..)

任何的想法？

Answer 1

我通过扩展 CairngormEvent 类并添加两个属性来实现这一点：

package control.events
{
    import com.adobe.cairngorm.control.CairngormEvent;

    public class AbstractCairngormEvent extends CairngormEvent
    {
        public var successHandler:Function;

        public var failureHandler:Function;

        public function AbstractCairngormEvent(type:String)
        {
            super(type);
        }
    }
}

并创建一个新类作为所有命令的基础，它实现了 ICommand：

package control.commands
{
    import com.adobe.cairngorm.commands.ICommand;
    import com.adobe.cairngorm.control.CairngormEvent;

    import control.events.AbstractCairngormEvent;

    /* This class is a base for all Commands. It allows the user to set callback 
        functions for successful completion and/or failure of the Command logic (i.e. 
        a WebService call). */
    public class CairngormCommand implements ICommand
    {
        private var successHandler:Function;

        private var failureHandler:Function;

        public function execute(event:CairngormEvent):void
        {
            if (event is AbstractCairngormEvent)
            {
                var commandEvent:AbstractCairngormEvent = 
                    event as AbstractCairngormEvent;

                successHandler = commandEvent.successHandler;

                failureHandler = commandEvent.failureHandler;
            }
        }

        public function notifyCallerOfSuccess():void
        {
            if (successHandler != null)
                successHandler.call(this);
        }

        public function notifyCallerOfFailure():void
        {
            if (failureHandler != null)
                failureHandler.call(this);
        }
    }
}

然后在每个 Command Class 中，当必要的逻辑完成，或者出现错误/失败时，我调用 CairngormCommand 基类中的相应函数。这是一个例子：

// Something like this would be in your view:

private function callSomeWebService():void {
    var event:WebServiceEvent = new WebServiceEvent();

    myEvent.successHandler = callMyEventSuccessHandler; 

    myEvent.failureHandler = callMyEventFailureHandler; 
}

private function callMyEventSuccessHandler():void {
    Alert.show("SUCCESS!!!");
}

private function callMyEventFailureHandler():void {
    Alert.show("FAILURE!!!");
}


// Here is the Event in your Controller:

package control.events
{
    import control.events.AbstractCairngormEvent;

    public class WebServiceEvent extends AbstractCairngormEvent
    {
        public static var EVENT_ID:String = "webService";

        public function WebServiceEvent()
        {
            super(EVENT_ID);
        }
    }
}

// And here is the Command in your Controller:

package control.commands
{
    import com.adobe.cairngorm.control.CairngormEvent;

    import control.commands.CairngormCommand;
    import control.events.WebServiceEvent;

    public class WebServiceCommand extends CairngormCommand
    {
        override public function execute(event:CairngormEvent):void
        {
            super.execute(event);

            ... // Call WebServices
        }
        ...

        private function webServiceResultHandler():void
        {
            // Handle results
            ...

            notifyCallerOfSuccess();
        }

        private function webServiceFaultHandler():void
        {
            // Handle fault
            ...

            notifyCallerOfFailure();
        }
    }
}

我现在只在我的 Cairngorm 应用程序中使用它。最好的部分是，如果您不需要成功和/或失败的回调，您可以将这些属性排除在事件实例化之外并简单地调度事件。

在加载显示之前加载显示所需数据的示例：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
    usePreloader="false" initialize="initializeHandler();">
    <mx:Script>
        <![CDATA[
            import control.events.InitializeApplicationEvent;

            private function initializeHandler():void
            {
                initializeApplication();
            }

            private function initializeApplication():void
            {
                var event:InitializeApplicationEvent = 
                    new InitializeApplicationEvent();

                event.successHandler = initializationSuccessHandler;

                event.dispatch();
            }

            private function initializationSuccessHandler():void
            {
                applicationContainer.visible = true;
            }
        ]]>
    </mx:Script>

    <control:Services xmlns:control="control.*" />

    <control:Controller xmlns:control="control.*" />

    <view:ApplicationContainer xmlns:view="view.*" id="applicationContainer" 
        width="100%" height="100%" visible="false" />
</mx:Application>

InitializeApplicationCommand（注意如何将事件和调用者链接起来，次数不限）：

package control.commands
{
    import com.adobe.cairngorm.control.CairngormEvent;

    import control.events.GetEvenMoreDataEvent;
    import control.events.GetSomeDataEvent;
    import control.events.GetSomeMoreDataEvent;
    import control.events.InitializeApplicationEvent;

    public class InitializeApplicationCommand extends CairngormCommand
    {
        override public function execute(event:CairngormEvent):void
        {
            super.execute(event);

            getSomeData();
        }

        private function getSomeData():void
        {
            var event:GetSomeDataEvent = new GetSomeDataEvent();

            event.successHandler = getSomeMoreData;

            event.failureHandler = errorHandler;

            event.dispatch();
        }

        private function getSomeMoreData():void
        {
            var event:GetSomeMoreDataEvent = new GetSomeMoreDataEvent();

            event.successHandler = getEvenMoreData;

            event.failureHandler = errorHandler;

            event.dispatch();
        }

        private function getEvenMoreData():void
        {
            var event:GetEvenMoreDataEvent = new GetEvenMoreDataEvent();

            event.successHandler = notifyCallerOfSuccess;

            event.failureHandler = errorHandler;

            event.dispatch();
        }

        private function errorHandler():void
        {
            alert.show("error");
        }
    }
}