Flex 文件上传导入组件

　　上文讲到Flex利用Blazeds来上传文件，本文则封装了一个组件用于文件的上传导入，其主要功能有：
　　1）文件的选择；
　　2）文件类型的限定，比如只能选择txt文件，图片文件等；
　　3）文件上传，利用Blazeds；
　　4）文件导入，利用Blazeds；
　　5）上传、导入的事件分发；
　　1、文件上传组件核心代码  flex/spark"                      xmlns:mx="library://ns.adobe.com/flex/mx" width="300" height="28" creationComplete="init()">                                                                                          -->                                        [Event(name="result", type="event.FileImportEvent")]                    [Event(name="fault", type=" event.FileImportEvent")]                                        3){
　　_fileFilter = [];
　　_fileFilter.push(new FileFilter("("+fileType+")",fileType));
　　}
　　}
　　// Property: maxFileSize，Flash Player Limit 100 mb
　　private var _maxFileSize:Number = 1024*1024*20;
　　[Bindable]
　　/**
　　* 读取和设置文件最大尺寸，单位为Byte,1K = 1024Byte,默认值为20M
　　*/
　　public function get maxFileSize():Number
　　{
　　return _maxFileSize;
　　} 
　　public function set maxFileSize(size:Number):void
　　{
　　_maxFileSize = size;
　　}
　　private function checkFile():Boolean{
　　var blnResult:Boolean = true;
　　if(StringUtil.isEmpty(txtFileInfo.text)){
　　Alert.show("请选择要上传的文件!");
　　return false;
　　}
　　if(file.size>_maxFileSize){    //文件大小验证失败
　　Alert.show(StringUtil.format("该文件尺寸{0} 超出最大尺寸 {1}.",file.size/1000,_maxFileSize/1000));
　　blnResult = false;
　　}
　　if(file.data==null){
　　Alert.show("文件正在加载中，请稍等!");
　　blnResult = false;
　　}
　　return blnResult;
　　}
　　protected function btnBrowse_clickHandler(event:MouseEvent):void
　　{
　　file.browse(_fileFilter);//打开文件选择框
　　}
　　protected function btnDelete_clickHandler(event:MouseEvent):void
　　{
　　//删除远程服务器的文件
　　//清空txtFileInfo
　　txtFileInfo.text = "";
　　txtFileInfo.toolTip = "";
　　}                               protected function ro_resultHandler(event:ResultEvent):void                             {                                      this.dispatchEvent(new FileImportEvent(FileImportEvent.RESULT,event.resul t));                             }                               protected function ro_faultHandler(event:FaultEvent):void                             {                                      this.dispatchEvent(new FileImportEvent(FileImportEvent.FAULT,null,event.f ault));                             }                                                          public function importFile(headers:Array):Boolean{                                      var isSuccess:Boolean = checkFile();                                      if(isSuccess){                                                ro.importFile(file.data,headers,file.type);                                      }                                      return isSuccess;                             }                                                          public function uploadFile():Boolean{                                      var isSuccess:Boolean = checkFile();                                      if(isSuccess){                                                ro.uploadFile(file.data,file.type);                                      }                                      return isSuccess;                             }                      ]]>                              width="25" id="btnBrowse" toolTip="选择文件" click="btnBrowse_clickHandler(event)"
　　paddingLeft="3" paddingRight="3" bottom="3" icon = "@Embed('assets/tool_folder_explore.png')"/>
　　width="25" id="btnDelete" icon = "@Embed('assets/tool_delete.png')"
　　labelPlacement="right" click="btnDelete_clickHandler(event)" paddingLeft="3" paddingRight="3" toolTip="取消文件选择"/>
　　 2、FileImportEvent事件 package event {     import flash.events.Event;          import mx.rpc.Fault;       publicclass FileImportEvent extends Event     {        publicstaticconst RESULT:String      = "result";        publicstaticconst FAULT:String       = "fault";        //        privatevar _result:Object;        privatevar _fault:Fault;         //        publicfunction FileImportEvent(type:String, result:Object=null, fault:Fault=null)        {            super(type,true);            this._result = result;            this._fault = fault;        }        //        publicfunctionget result():Object{            return _result;        }        publicfunctionset result(value:Object):void{            _result = value;        }        //        publicfunctionget fault():Fault{            return _fault;        }        publicfunctionset fault(value:Fault):void{            _fault = value;        }     } } 3、示例  flex/spark"                xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="800" minHeight="600" creationComplete="init()" width="370" height="180"                xmlns:fileupload="whh.flex.controls.fileupload.*">