何时/如何初始化 URL 请求

Question

我做了一个图像上传管理器。我最初是在 Flash Develop 中将其作为 AS 类制作的。我需要将其转换为 Flash Builder 4.5 中的组件。它作为 .swf 工作得非常好，但我不知道如何使 URL 请求在 Flash Builder 中工作。这是我在标签之间的内容：

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
           xmlns:s="library://ns.adobe.com/flex/spark" 
           xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"
           creationComplete="init()">
<fx:Script>
    <![CDATA[
        import flash.display.MovieClip;
        import flash.display.*;
        import flash.events.*;
        import flash.text.*;

        import flash.net.FileReference;
        import flash.net.FileReferenceList;
        import flash.net.FileFilter;
        import flash.net.URLRequest;
        import flash.utils.Timer;
        import flash.events.TimerEvent;

        public var file:FileReference;
        public var filefilters:Array;
        public var req:URLRequest;
        public var tm:Timer;
        public var speed:Number = 0;
        public var currbytes:Number = 0;
        public var lastbytes:Number = 0;


        public function init():void{
            req = new URLRequest();
            req.url = ( stage.loaderInfo.parameters.f )? stage.loaderInfo.parameters.f : 'http://www.listgiant.com/LG/upload.php';
            file = new FileReference();
            setup( file );
            select_btn.addEventListener( MouseEvent.CLICK, browse );
            tm = new Timer( 1000 );
            tm.addEventListener( TimerEvent.TIMER, updateSpeed );
        }


        public function browse( e:MouseEvent ):void{
            filefilters = [ new FileFilter('Images', '*.jpg') ]; // add other file filters
            file.browse( filefilters );
        }

        private function setup( file:FileReference ):void{
            file.addEventListener( IOErrorEvent.IO_ERROR, io_error );
            file.addEventListener( Event.OPEN, open_func );
            file.addEventListener( Event.SELECT, selectHandler );
            file.addEventListener( DataEvent.UPLOAD_COMPLETE_DATA, show_message );      
        }
        private function io_error( e:IOErrorEvent ):void{
            label_txt.text = 'The file could not be uploaded.';
            tm.stop();
        }

        private function open_func( e:Event ):void{
            tm.start();
        }

        private function selectHandler( e:Event ):void{
            file.upload( req );

        }

        private function show_message( e:DataEvent ):void{
            tm.stop();
            if( e.data == 'ok' ){
                label_txt.text = 'The file has been uploaded.';
            } else if( e.data == 'error'){
                label_txt.text = 'The file could not be uploaded.';
            }
        }

        private function updateSpeed( e:TimerEvent ):void{
            speed = Math.round( (currbytes - lastbytes)/1024 );
            lastbytes = currbytes;
        }

        private function cancelUpload( e:MouseEvent ):void{
            file.cancel();
            reset();
        }

        private function reset():void{
            select_btn.visible = true;
            label_txt.text = '';
        }
]]>
</fx:Script>



<s:Button id="select_btn" label="Upload" click="browse(event)"/>
<s:Label id="label_txt" text=""/>

我没有放置 mxml 控件，但在显示各种状态消息的按钮下有一个浏览按钮 (id="selects_btn") 和一个标签 (id="label_txt")。

我尝试将 init 函数添加到组件的creationComplete 事件中。我收到错误消息说访问空对象。

Answer 1

也许 stage 对象为 null。在 声明中添加 applicationComplete 属性并将值设置为 init() 方法，如下所示:

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx"
               applicationComplete="init()">

Answer 2

没有行号，我只能猜测，但也许 select_btn 在这一行为空：

select_btn.addEventListener( MouseEvent.CLICK, browse );

您可以将事件侦听器放在 btn 本身上：

<s:Button id="select_bt" click="browse(event)" />