Flex与后台交互的4种方法 HTTPService、URLLoader、WebService详解

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="initializeHandler(event)"><mx:Script><![CDATA[private function initializeHandler(event:Event):void {countriesService.send();}private function changeHandler(event:Event):void {statesService.send();}]]></mx:Script><!-- 载入纯静态的xml数据 --><mx:HTTPService id="countriesService" url="http://www.rightactionscript.com/states/xml/countries.xml" /><!-- 载入由php生成的xml数据 --><mx:HTTPService id="statesService" url="http://www.rightactionscript.com/states/xml/states.php"><!-- 以下标签就是要发送到服务端的数据了,可以这样理解:有一个名为country的变量,它的值为花括号{}里的内容 --><mx:request><country>{country.value}</country></mx:request></mx:HTTPService><mx:VBox><!-- 此控件的数据由第一个<mx:HTTPService/>控件接收的内容提供,并且由这个ComboBox控制着第二个ComboBox所要显示的内容 --><mx:ComboBox id="country" dataProvider="{countriesService.lastResult.countries.country}"change="changeHandler(event)" /><!-- 下面的ComboBox已经绑定了{statesService.lastResult.states.state},随它的数据改变而改变 --><mx:ComboBox dataProvider="{statesService.lastResult.states.state}" /></mx:VBox></mx:Application>

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="initializeHandler(event)"><mx:Script><![CDATA[private var _countriesService:URLLoader;private var _statesService:URLLoader;private function initializeHandler(event:Event):void {_countriesService = new URLLoader();_countriesService.addEventListener(Event.COMPLETE, countriesCompleteHandler);_countriesService.load(new URLRequest("http://www.rightactionscript.com/states/xml/countries.xml"));_statesService = new URLLoader();_statesService.addEventListener(Event.COMPLETE, statesCompleteHandler);XML.ignoreWhitespace = true;}private function countriesCompleteHandler(event:Event):void {var xml:XML = new XML(_countriesService.data);country.dataProvider = xml.children();}private function statesCompleteHandler(event:Event):void {var xml:XML = new XML(_statesService.data);state.dataProvider = xml.children();}private function changeHandler(event:Event):void {var request:URLRequest = new URLRequest("http://www.rightactionscript.com/states/xml/states.php");var parameters:URLVariables = new URLVariables();parameters.country = country.value;request.data = parameters;_statesService.load(request);}]]></mx:Script><mx:VBox><mx:ComboBox id="country" change="changeHandler(event)" /><mx:ComboBox id="state" /></mx:VBox></mx:Application>

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" initialize="initializeHandler(event)"><mx:Script><![CDATA[private function initializeHandler(event:Event):void {statesService.getCountries();}private function changeHandler(event:Event):void {statesService.getStates(country.value);}]]></mx:Script><mx:WebService id="statesService"wsdl="http://www.rightactionscript.com/states/webservice/StatesService.php?wsdl"><mx:operation name="getCountries" /><mx:operation name="getStates" /></mx:WebService><mx:VBox><mx:ComboBox id="country"dataProvider="{statesService.getCountries.lastResult}" change="changeHandler(event)" /><mx:ComboBox dataProvider="{statesService.getStates.lastResult}" /></mx:VBox></mx:Application>