Using an XML Configuration File for Flex
Okay, if you are a new Flex developer in training and are going to use a configuration file for your appliation, you might be tempted as I was to do it all in Actionscript code using the URLLoader class. While you can do this, it takes a lot of elbow grease to get the timing just right.
My best experience was using the <mx:HTTPService> tag to load the configuration file and process it into the e4x parsing model as shown:
Let's say you have the following configuration file:
XML:
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<?xml version="1.0" encoding="UTF-8"?>
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<botconfig>
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<botname>Andy Richards</botname>
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<picture>andyRichards.gif</picture>
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<backgroundStyle>insideRoomTablesBed</backgroundStyle>
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</botconfig>
Now you want to read that in and assign the contents of each node to a configuration settings object:
Actionscript:
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/*
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ConfigSettings.as
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ConfigSettings class defines a custom object for
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parsing a configuration xml file and distributing the
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nodes to fields of the object so they are easily accessible to
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the main Flex Application.
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*/
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package edu.asu.simlandia {
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public class ConfigSettings {
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private var _botName:String;
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private var _botImage:String;
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private var _backgroundStyle:String;
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private var xmlDoc:XML;
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public function get botName():String {
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return this._botName;
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}
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public function get botImage():String {
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return this._botImage;
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}
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public function get backgroundStyle():String {
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return this._backgroundStyle;
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}
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public function ConfigSettings():void {
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this._interactions = new Array();
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}
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public function set botName(value:String):void {
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this._botName = value;
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}
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public function set botImage(value:String):void {
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this._botImage = value;
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}
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public function set backgroundStyle(value:String):void {
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this._backgroundStyle = value;
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}
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/*
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Function responsible for loading the configuration file,
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parsing it, and assigning the text properties to the
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configuration object
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*/
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public function loadData(xmlData:XML):void {
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this.xmlDoc = xmlData;
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this.botImage = this.xmlDoc.picture;
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this.botName = this.xmlDoc.botname;
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this.backgroundStyle = this.xmlDoc.backgroundStyle;
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}
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}
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}
Use the following MXML code to do it:
XML:
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<mx:Application
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xmlns:mx="http://www.adobe.com/2006/mxml"
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layout="absolute" backgroundColor="#CCCC99"
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creationComplete="configService.send()">
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<mx:Script>
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<![CDATA[
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import edu.asu.simlandia.*;
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import mx.rpc.events.ResultEvent;
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private var settings:ConfigSettings;
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private var configXML:XML;
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private function configure(event:ResultEvent):void {
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settings = new ConfigSettings();
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settings.loadData(this.configXML);
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this.botName = this.settings.botName;
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this.botImage = "images/" + this.settings.botImage;
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this.styleName = this.settings.backgroundStyle;
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}
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]]>
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</mx:Script>
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<mx:HTTPService url="configFile.xml" id="configService" resultFormat="e4x" result="configure(event)"/>
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</mx:Application>
