As3模拟我的电脑，并实现'A'键后退，鼠标拖动文件夹

package src {import flash.display.Sprite;import flash.filesystem.File;import flash.display.Bitmap;import flash.events.MouseEvent;import flash.text.TextField;import flash.text.TextFormat;import flash.events.TextEvent;import flash.events.KeyboardEvent;import flash.ui.Keyboard;import flash.geom.Rectangle;public class Main extends Sprite {public const fu:String = "\\";public var fmt:TextFormat = new TextFormat(null,12,null,null,null,null,null,null,"center");public var f:File = new File;public var nav:TextField = new TextField;private var div:Sprite = new Sprite;private var num:uint = 0;private var n:uint = 0;private var isdrag:Boolean = false;public function Main() {nav.x = nav.y = 10;//导航nav.width = 780;nav.height = 20;nav.type = "input";nav.border = true;addChild(nav);nav.addEventListener(TextEvent.LINK,link);       //链接监听stage.addEventListener(KeyboardEvent.KEY_DOWN,kd);  //键盘监听addChild(div);div.y = 40;view(File.getRootDirectories());  //得到根目录  返回一个数组  C:\  D:\this.addEventListener(MouseEvent.DOUBLE_CLICK,click);   //鼠标监听this.addEventListener(MouseEvent.MOUSE_DOWN,down);this.addEventListener(MouseEvent.MOUSE_UP,up);}private function kd(a:KeyboardEvent):void{switch(a.keyCode){case Keyboard.ENTER:f.nativePath = nav.text;if(f.exists){openFile();}break;case 65:case Keyboard.BACK:if(n > 0){gotoDir(--n);}break;}}private function view(a:Array):void{while(div.numChildren) div.removeChildAt(0);   for(var i:int = 0;i<a.length;i++){div.addChild(icon(a[i] as File,i));}}private function icon(f:File,i:int):Sprite{var s:Sprite = new Sprite;var t:TextField = new TextField;var b:Bitmap = new Bitmap(f.icon.bitmaps[0]);s.doubleClickEnabled = true;    //打开鼠标双击许可s.alpha = f.isHidden?0.5:1;s.name = f.nativePath;t.defaultTextFormat = fmt;t.text = f.name;t.y = 32;t.width = 40;t.height = 20;s.addChild(t);s.addChild(b);s.x = (i%20) *40;s.y = int(i/20)*60;return s;}private function click(e:MouseEvent):void{if(e.target is TextField)return;f.nativePath = e.target.name;nav.htmlText =setlink(f.nativePath);n = nav.text.split(fu).length - 1;openFile();}private function down(e:MouseEvent):void{if(!isdrag){e.target.startDrag(); //允许组建可拖动}}private function up(e:MouseEvent):void{e.target.stopDrag();   //停止组建拖动isdrag = false;}private function openFile():void{if(f.isDirectory)view(f.getDirectoryListing());elsef.openWithDefaultApplication();  }private function setlink(s:String,t:String= "我的电脑\\"):String{var m:Array = (t+s).split(fu);num = m.length - 1;t = "";for(var i:int=0;  i<m.length-1; i++){t += '<a href="event:'+i+'">'+m[i]+fu+'</a>';}return t+m.pop();}private function link(e:TextEvent):void{gotoDir(Number(e.text));n = nav.text.split(fu).length - 1;}private function gotoF(n:uint):void{if(n == 0){view(File.getRootDirectories());nav.htmlText =setlink("");return;}f.nativePath = nav.text.replace("我的电脑\\","").split(fu, n).join(fu);nav.htmlText =setlink(f.nativePath);view(f.getDirectoryListing());}private function gotoDir(n:uint):void{if(n == 0){view(File.getRootDirectories());nav.htmlText =setlink("");return;}f.nativePath = nav.text.replace("我的电脑\\","").split(fu, n).join(fu);nav.htmlText =setlink(f.nativePath);view(f.getDirectoryListing());}}}