flex app

<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"
      initialize="application1_initializeHandler(event)"
      preloader="com.wks.OverWriteLoadBar"
      skinClass="com.wks.skins.MyApplicationSkin"
      xmlns:widget="widget.*" xmlns:local="*">

</s:Application>

package com.wks
{
 import flash.display.*;
 import flash.events.*;
 import flash.net.*;
 import flash.text.TextField;
 import flash.text.TextFormat;
 
 import mx.events.FlexEvent;
 import mx.preloaders.DownloadProgressBar;
 
 public class OverWriteLoadBar extends DownloadProgressBar
 {
  private var logo:Loader;
  private var txt:TextField;
  private var _preloader:Sprite;
  
  public function OverWriteLoadBar()
  {
   
   logo = new Loader();
   logo.load(new URLRequest("images/logo.png")); //其中中間顯示的圖片
   addChild(logo);
   
   var style:TextFormat = new TextFormat(null,null,0x000000,null,null,null,null,null,"center");
   txt = new TextField(); //提示信息
   txt.defaultTextFormat = style;
   txt.width = 200;
   txt.selectable = false;
   txt.height = 20;
   addChild(txt);
   
   super();
  }
  override public function set preloader(value:Sprite):void{
   _preloader = value
   _preloader.addEventListener(ProgressEvent.PROGRESS,load_progress);
   _preloader.addEventListener(Event.COMPLETE,load_complete);
   _preloader.addEventListener(FlexEvent.INIT_PROGRESS,init_progress);
   _preloader.addEventListener(FlexEvent.INIT_COMPLETE,init_complete);
   
   stage.addEventListener(Event.RESIZE,resize)
   resize(null);
  }
  private function remove():void{
   _preloader.removeEventListener(ProgressEvent.PROGRESS,load_progress);
   _preloader.removeEventListener(Event.COMPLETE,load_complete);
   _preloader.removeEventListener(FlexEvent.INIT_PROGRESS,init_progress);
   _preloader.removeEventListener(FlexEvent.INIT_COMPLETE,init_complete);
   stage.removeEventListener(Event.RESIZE,resize)
  }
  private function resize(e:Event):void{
   logo.x = (stage.stageWidth - 302)/2;
   logo.y = (stage.stageHeight - 102)/2;
   txt.x = (stage.stageWidth - 150)/2;
   txt.y = logo.y + 40+102;
   
   graphics.clear();
   graphics.beginFill(0xEEFAFF); //加載時候的背景顏色
   graphics.drawRect(0,0,stage.stageWidth,stage.stageHeight); //設置寬高，這裏設置和舞臺高寬一樣
   graphics.endFill();
  }
  
  //四個階段，加載，加載完成，初始化，初始化完成。
  private function load_progress(e:ProgressEvent):void{
   var progress:Number = 0;
   if ( e.bytesTotal > 0.1 )
   {
    // 張小寧注：這裏要防範被零除
    progress = e.bytesLoaded/e.bytesTotal*100;
   }
   txt.text = "正在加載..." + String(int(progress)) + "%";
  }
  private function load_complete(e:Event):void{
   txt.text = "加載完畢!"
  }
  private function init_progress(e:FlexEvent):void{
   txt.text = "正在初始化..."
  }
  private function init_complete(e:FlexEvent):void{
   txt.text = "初始化完畢!"
   remove()
   dispatchEvent(new Event(Event.COMPLETE))
  }
  
 }
}

/**控制application的高度和寬度只需要設置application下第一個ui的minheight和minwidth即可*/

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/11/03/adding-scroll-bars-to-an-spark-application-container-in-flex-4/ -->
<s:Skin name="MyApplicationSkin"
  xmlns:fx="http://ns.adobe.com/mxml/2009"
  xmlns:s="library://ns.adobe.com/flex/spark"
  xmlns:fb="http://ns.adobe.com/flashbuilder/2009"
  alpha.disabledStates="0.5">
 <!-- states -->
 <s:states>
  <s:State name="normal" stateGroups="normalStates" />
  <s:State name="disabled" stateGroups="disabledStates" />
  <s:State name="normalWithControlBar" stateGroups="normalStates" />
  <s:State name="disabledWithControlBar" stateGroups="disabledStates" />
 </s:states>
 
 <fx:Metadata>
  [HostComponent("spark.components.Application")]
 </fx:Metadata>
 
 <fx:Script fb:purpose="styling">
  <![CDATA[
   override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void {
    super.updateDisplayList(unscaledWidth, unscaledHeight);
   }
  ]]>
 </fx:Script>
 
 <!-- fill -->
 <!---
 A rectangle with a solid color fill that forms the background of the application.
 The color of the fill is set to the Application's backgroundColor property.
 -->
 <s:Group left="0" right="0" top="0" bottom="0">
  <s:layout>
   <s:VerticalLayout gap="0" verticalAlign="middle" />
  </s:layout>
  <s:Scroller id="contentScroller" width="100%" height="100%">
   <s:Group id="contentGroup" minWidth="0" minHeight="0" />
  </s:Scroller>
 </s:Group>
 
</s:Skin>