Flex中利用URLLoader和URLVariables类导入文件的例子

Peter在写这个例子的时候说“Not sure if this is helpful to anybody”，其他人不敢说，不过这个例子刚好是我所需要的–我在做的一个解析ActionScript文件的项目中需要用到这个功能。例子中演示了如何利用URLLoader和URLVariables类，从一个扩展文件中读入一定格式的内容（name/value），根据读入的内容随即显示在DataGrid控件中。

下面是完整代码：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="horizontal" verticalAlign="middle" backgroundColor="white" creationComplete="init()"> 

    <mx:Script>
        <!--[CDATA[
            import mx.collections.ArrayCollection; 

            [Bindable]
            private var VARIABLES_URL:String = "params.txt"; 

            [Bindable]
            private var arrColl:ArrayCollection; 

            [Bindable]
            private var paramColl:ArrayCollection; 

            private var urlReq:URLRequest;
            private var urlLdr:URLLoader; 

            private function init():void {
                /* Initialize the two ArrayCollections objects with empty arrays. */
                arrColl = new ArrayCollection();
                paramColl = new ArrayCollection(); 

                /* Initialize the URLRequest object with the URL to the file of name/value pairs. */
                urlReq = new URLRequest(VARIABLES_URL); 

                /* Initialize the URLLoader object, assign the various event listeners, and load the specified URLRequest object. */
                urlLdr = new URLLoader();
                urlLdr.addEventListener(Event.COMPLETE, doEvent);
                urlLdr.addEventListener(Event.OPEN, doEvent);
                urlLdr.addEventListener(HTTPStatusEvent.HTTP_STATUS, doEvent);
                urlLdr.addEventListener(IOErrorEvent.IO_ERROR, doEvent);
                urlLdr.addEventListener(ProgressEvent.PROGRESS, doEvent);
                urlLdr.addEventListener(SecurityErrorEvent.SECURITY_ERROR, doEvent);
                urlLdr.load(urlReq);
            } 

            private function doEvent(evt:Event):void {
                arrColl.addItem({type:evt.type, idx:arrColl.length+1, eventString:evt.toString()}); 

                switch (evt.type) {
                    case Event.COMPLETE:
                        /* If the load was successful, create a URLVariables object from the URLLoader.data property and populate the paramColl ArrayCollection object. */
                        var ldr:URLLoader = evt.currentTarget as URLLoader;
                        var vars:URLVariables = new URLVariables(ldr.data);
                        var key:String; 

                        for (key in vars) {
                            paramColl.addItem({key:key, value:vars[key]});
                        } 

                        params.visible = true;
                        break;
                }
            }
        ]]-->
    </mx:Script> 

    <mx:VBox>
        <mx:Label text="Events:" />
        <mx:DataGrid id="events" dataProvider="{arrColl}" rowCount="5">
            <mx:columns>
                <mx:DataGridColumn dataField="idx" headerText="#" width="20" />
                <mx:DataGridColumn dataField="type" headerText="Type" showDataTips="true" dataTipField="eventString" />
            </mx:columns>
        </mx:DataGrid>
    </mx:VBox> 

    <mx:VBox>
        <mx:Label text="Parameters:" />
        <mx:DataGrid id="params" dataProvider="{paramColl}" rowCount="5" visible="false">
            <mx:columns>
                <mx:DataGridColumn dataField="key" headerText="Key" />
                <mx:DataGridColumn dataField="value" headerText="Value" />
            </mx:columns>
        </mx:DataGrid>
    </mx:VBox> 

</mx:Application>
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