Flex通信篇——Flex和外部进行异步通信

彭博 发布于 2012/03/09 12:24
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ExternalInterface.call的问题

请留意以下情景,要利用外部应用程序弹出文件选择窗体,并返回所选的文件路径。

使用ExternalInterface.call来实现,当用户60秒(Flex已经设置最长的等待时间)内未能够完成文件选择会弹出"1502"的错误,严重影响用户体现。

所以,一些比较耗时的操作(超过60s),或无法确定何时调用完成的方法(如上述),应该使用异步调用的方式,当方法执行完成后进行回调。

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实现异步调用机制

Flex端

定义一个Dictionary,用来缓存回调的方法

private var m_AsyncDict:Dictionary;

 

定义OpenFileDialogAsync方法,用fscommand来实现,fscommand是单向的调用,不存在60秒超时的问题。

//弹出打开文件窗口,选择单个文件

public function OpenFileDialogAsync(title:String = "请选择1个文件", initFolder:String = "", filter:String = "", callbackString:Function = null):void

{

    //创建异步ID

    var id:String = mx.utils.UIDUtil.createUID();

    //创建自定义异步请求

    var request:String = "<args>";

    request += "<arg>" + id + "</arg>";

    request += "<arg>" + title + "</arg>";

    request += "<arg>" + initFolder + "</arg>";

    request += "<arg>" + filter + "</arg>";

    request += "</args>";

    //缓存回调方法

    if (callbackString != null)

        m_AsyncDict[id] = callbackString;

    flash.system.fscommand(FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC, request);

}

定义并注册AsyncCallback和CancelAsyncCall方法,让外部应用程序能够响应异步回调或取消异步回调。

public function AsyncCallback(id:String, value:Object):void

{

    if (m_AsyncDict[id])

    {

        //执行回调方法

        m_AsyncDict[id](value);

        delete m_AsyncDict[id];

    }

}

public function CancelAsyncCall(id:String):void

{

    if (m_AsyncDict[id])

    {

        delete m_AsyncDict[id];

    }

}

if (ExternalInterface.available)

{

    ExternalInterface.addCallback(APP_TO_FLASH_ASYNC_CALLBACK, AsyncCallback);

    ExternalInterface.addCallback(APP_TO_FLASH_CANCEL_ASYNC_CALL, CancelAsyncCall);

}

EXE端

为ShockwaveFlashObject注册FSCommand事件,并添加事件处理的方法。

axShockwaveFlash1.FlashCall += new AxShockwaveFlashObjects._IShockwaveFlashEvents_FlashCallEventHandler(axShockwaveFlash1_FlashCall);

void axShockwaveFlash1_FSCommand(object sender, AxShockwaveFlashObjects._IShockwaveFlashEvents_FSCommandEvent e)

{

//请求e.args是自定义Xml格式

XmlDocument request = new XmlDocument();

request.LoadXml(e.args);

if (e.command == FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC)

{

//获取回调的键值

string asyncId = request.DocumentElement.ChildNodes[0].InnerText;

//获取窗体参数

string title = request.DocumentElement.ChildNodes[1].InnerText;

string initFolder = request.DocumentElement.ChildNodes[2].InnerText;

string filter = request.DocumentElement.ChildNodes[3].InnerText;

using (OpenFileDialog dlg = new OpenFileDialog())

{

dlg.Title = title;

dlg.InitialDirectory = initFolder;

dlg.Filter = filter;

if (dlg.ShowDialog() == DialogResult.OK)

{

AsyncCallback(asyncId, dlg.FileName);

}

else

{

CancelAsyncCall(asyncId);

}

}

}

}

定义2个方法调用Flex里注册的AsyncCallback和CancelAsyncCall方法。

//异步回调

public void AsyncCallback(string asyncId, string value)

{

StringBuilder sb = new StringBuilder();

sb.Append("<invoke name=/"").Append(APP_TO_FLASH_ASYNC_CALLBACK).Append("/" returntype=/"xml/">");

sb.Append("<arguments>");

sb.Append("<string>").Append(asyncId).Append("</string>");

sb.Append("<string>").Append(value).Append("</string>");

sb.Append("</arguments>");

sb.Append("</invoke>");

axShockwaveFlash1.CallFunction(sb.ToString());

}

//撤销异步回调

private void CancelAsyncCall(string asyncId)

{

StringBuilder sb = new StringBuilder();

sb.Append("<invoke name=/"").Append(APP_TO_FLASH_CANCEL_ASYNC_CALL).Append("/" returntype=/"xml/">");

sb.Append("<arguments>");

sb.Append("<string>").Append(asyncId).Append("</string>");

sb.Append("</arguments>");

sb.Append("</invoke>");

axShockwaveFlash1.CallFunction(sb.ToString());

}

完整代码

Flex端

LocalAPI.as

package

{

    import flash.external.ExternalInterface;

    import flash.system.fscommand;

    import flash.utils.Dictionary;

    import mx.utils.UIDUtil;

    public class LocalAPI

    {

        //通讯命令定义

        private static const FLASH_TO_APP_OPEN_FILE_DIALOG:String = "OpenFileDialog";

        private static const FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC:String = "OpenFileDialogAsync";        

        private static const APP_TO_FLASH_ASYNC_CALLBACK:String = "AsyncCallback";

        private static const APP_TO_FLASH_CANCEL_ASYNC_CALL:String = "CancelAsyncCall";

        //Async dict

        private var m_AsyncDict:Dictionary;

        //Singleton static obj

        private static var g_Instance:LocalAPI = null;

        //获取LocalAPI单件实例

        public static function get Instance():LocalAPI

        {

            if (g_Instance == null)

            {

                g_Instance = new LocalAPI();

            }

            return g_Instance;

        }

        public function LocalAPI()

        {

            if (g_Instance != null)

                throw new Error("Singleton class. Please use Instance static filed.");

            m_AsyncDict = new Dictionary();

            if (ExternalInterface.available)

            {

                ExternalInterface.addCallback(APP_TO_FLASH_ASYNC_CALLBACK, AsyncCallback);

                ExternalInterface.addCallback(APP_TO_FLASH_CANCEL_ASYNC_CALL, CancelAsyncCall);

            }

        }

        //弹出打开文件窗口,选择单个文件(60s局限)

        public function OpenFileDialog(title:String = "请选择1个文件", initFolder:String = "", filter:String = ""):String

        {

            if(!ExternalInterface.available) return null;

            return ExternalInterface.call(FLASH_TO_APP_OPEN_FILE_DIALOG, title, initFolder, filter);

        }

        //异步通信

        //弹出打开文件窗口,选择单个文件

        public function OpenFileDialogAsync(title:String = "请选择1个文件", initFolder:String = "", filter:String = "", callbackString:Function = null):void

        {

            //创建异步ID

            var id:String = mx.utils.UIDUtil.createUID();

            //创建自定义异步请求

            var request:String = "<args>";

            request += "<arg>" + id + "</arg>";

            request += "<arg>" + title + "</arg>";

            request += "<arg>" + initFolder + "</arg>";

            request += "<arg>" + filter + "</arg>";

            request += "</args>";

            //缓存回调方法

            if (callbackString != null)

                m_AsyncDict[id] = callbackString;

            flash.system.fscommand(FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC, request);

        }

        public function AsyncCallback(id:String, value:Object):void

        {

            if (m_AsyncDict[id])

            {

                //执行回调方法

                m_AsyncDict[id](value);

                delete m_AsyncDict[id];

            }

        }

        public function CancelAsyncCall(id:String):void

        {

            if (m_AsyncDict[id])

            {

                delete m_AsyncDict[id];

            }

        }

    }

}

Demo.mxml

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

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" fontSize="12">

    <mx:Script>

        private function GetFilePath():void

        {

            var path:String = LocalAPI.Instance.OpenFileDialog();

            if (path != null)

                _Path1.text = path;

        }

            //异步方式

        private function GetFilePathAsync():void

        {

            LocalAPI.Instance.OpenFileDialogAsync("请选择1个文件", "", "", function(result:String):void

            {

                _Path2.text = result;

            });

        }

    </mx:Script>

    <mx:Button x="445.75" y="100" label="浏览1" click="GetFilePath()"/>

    <mx:Button x="445.75" y="147" label="浏览2" click="GetFilePathAsync()"/>

    <mx:Label x="71" y="102" text="文件路径"/>

    <mx:TextInput x="188.25" y="100" width="249.5" id="_Path1"/>

    <mx:TextInput x="188.25" y="147" width="249.5" id="_Path2"/>

    <mx:Label x="71" y="149" text="文件路径(异步方式)"/>

    <mx:Text x="71" y="196" width="459.75" height="213" id="_Trace"/>

</mx:Application>

EXE端

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Xml;

 

namespace WinFormDemo

{

    public partial class Form1 : Form

    {

        //定义通信命令

        private string FLASH_TO_APP_OPEN_FILE_DIALOG = "OpenFileDialog";

        private string FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC = "OpenFileDialogAsync";

        private string APP_TO_FLASH_ASYNC_CALLBACK = "AsyncCallback";

        private string APP_TO_FLASH_CANCEL_ASYNC_CALL = "CancelAsyncCall";

        private bool m_Init = false;

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            if (m_Init) return;

            string swf = System.IO.Path.Combine(Application.StartupPath, "Demo.swf");

            axShockwaveFlash1.FSCommand += new AxShockwaveFlashObjects._IShockwaveFlashEvents_FSCommandEventHandler(axShockwaveFlash1_FSCommand);

            axShockwaveFlash1.FlashCall += new AxShockwaveFlashObjects._IShockwaveFlashEvents_FlashCallEventHandler(axShockwaveFlash1_FlashCall);

            axShockwaveFlash1.Movie = swf;

            m_Init = true;

        }

        void axShockwaveFlash1_FlashCall(object sender, AxShockwaveFlashObjects._IShockwaveFlashEvents_FlashCallEvent e)

        {

            //请求e.request是Xml格式,详细请查阅文档

            XmlDocument request = new XmlDocument();

            request.LoadXml(e.request);

            string command = request.DocumentElement.Attributes["name"].Value;

            if (command == FLASH_TO_APP_OPEN_FILE_DIALOG)

            {

                //获取窗体参数

                string title = request.DocumentElement.ChildNodes[0].ChildNodes[0].InnerText;

                string initFolder = request.DocumentElement.ChildNodes[0].ChildNodes[1].InnerText;

                string filter = request.DocumentElement.ChildNodes[0].ChildNodes[2].InnerText;

                using (OpenFileDialog dlg = new OpenFileDialog())

                {

                    dlg.Title = title;

                    dlg.InitialDirectory = initFolder;

                    dlg.Filter = filter;

                    if (dlg.ShowDialog() == DialogResult.OK)

                    {

                        axShockwaveFlash1.SetReturnValue("<string>" + dlg.FileName + "</string>");

                    }

                    else

                    {

                        axShockwaveFlash1.SetReturnValue("<null/>");

                    }

                }

            }

        }

 

        void axShockwaveFlash1_FSCommand(object sender, AxShockwaveFlashObjects._IShockwaveFlashEvents_FSCommandEvent e)

        {

            //请求e.args是自定义Xml格式

            XmlDocument request = new XmlDocument();

            request.LoadXml(e.args);

            if (e.command == FLASH_TO_APP_OPEN_FILE_DIALOG_ASYNC)

            {

                //获取回调的键值

                string asyncId = request.DocumentElement.ChildNodes[0].InnerText;

                //获取窗体参数

                string title = request.DocumentElement.ChildNodes[1].InnerText;

                string initFolder = request.DocumentElement.ChildNodes[2].InnerText;

                string filter = request.DocumentElement.ChildNodes[3].InnerText;

                using (OpenFileDialog dlg = new OpenFileDialog())

                {

                    dlg.Title = title;

                    dlg.InitialDirectory = initFolder;

                    dlg.Filter = filter;

                    if (dlg.ShowDialog() == DialogResult.OK)

                    {

                        AsyncCallback(asyncId, dlg.FileName);

                    }

                    else

                    {

                        CancelAsyncCall(asyncId);

                    }

                }

            }

        }

        //异步回调

        public void AsyncCallback(string asyncId, string value)

        {

            StringBuilder sb = new StringBuilder();

            sb.Append("<invoke name=/"").Append(APP_TO_FLASH_ASYNC_CALLBACK).Append("/" returntype=/"xml/">");

            sb.Append("<arguments>");

            sb.Append("<string>").Append(asyncId).Append("</string>");

            sb.Append("<string>").Append(value).Append("</string>");

            sb.Append("</arguments>");

            sb.Append("</invoke>");

            axShockwaveFlash1.CallFunction(sb.ToString());

        }

        //撤销异步回调

        private void CancelAsyncCall(string asyncId)

        {

            StringBuilder sb = new StringBuilder();

            sb.Append("<invoke name=/"").Append(APP_TO_FLASH_CANCEL_ASYNC_CALL).Append("/" returntype=/"xml/">");

            sb.Append("<arguments>");

            sb.Append("<string>").Append(asyncId).Append("</string>");

            sb.Append("</arguments>");

            sb.Append("</invoke>");

            axShockwaveFlash1.CallFunction(sb.ToString());

        }

    }

}

系列索引

Flex通信篇——Flex和外部应用程序进行通信

Flex通信篇——Flex和外部进行异步通信

Flex通信篇——Flex键盘组合键

Flex通信篇——构建企业级HTTP通信层

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原文链接:http://blog.csdn.net/hunkcai/article/details/5098666
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