flex文件下载

1flex端

<mx:Button label="下 载" click="download()"/>

//下载
  public function download():void{
   var str:String=this.uploadfiles.selectedIndex.toString();
   if(str=="-1"){
    Alert.show("请选中要下载的文件");
   }else{
    downloadfiles();
   }
  }
  public function downloadfiles():void{
   var loadid:String=this.uploadfiles.selectedItem.loadid;
   if(loadid==null || loadid==""){
      Alert.show("对不起，该文件还未上传");
      }    
      var urlAddress:String=model.root+"/uploadFiles.do?method=download&loadid="+loadid;   
      //URLRequest可以捕获单个HTTP的所有信息
      var url:URLRequest=new URLRequest(urlAddress);
         var loadname:String=this.uploadfiles.selectedItem.loadname;
         //download()方法提示用户提供文件的保存位置并开始从远程 URL 进行下载。
         filedown.download(url,loadname);
  }
  protected override  function createChildren():void{
   super.createChildren();
   filedown.addEventListener(Event.COMPLETE,onDownCompleted);
  }
  public  function  onDownCompleted(evt:Event):void{
     this.resultlabel.visible=true;
        var fileref:FileReference = evt.currentTarget as FileReference;
        resultlabel.text = "文件名:" + uploadfiles.selectedItem.loadname+ "下载完毕！";     
  }

 

java后台(action)

 /**
  * 文件下载
  *
  * @param mapping
  * @param form
  * @param request
  * @param response
  * @return
  */
 public ActionForward download(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response)
   throws Exception {
  log.info("Enter UploadFilesAction download===============");
  // 被下载的文件id
  String loadid = request.getParameter("loadid");
  UploadFiles condition = this.uploadService.getFiles(loadid);
  // 读取文件存放的目录
  String filepath = this.getServlet().getServletContext().getRealPath("");
  // 页面中的文件路径与服务器上的路径匹配(与服务器有关吗？？)

  // File file = new File(filepath, condition.getLoadpath());
  File file = new File(condition.getLoadpath());
  // 如果文件存在(读取文件流)
  if (file.exists()) {
   response.reset();
   response.setContentType("application/x-msdownload");
   response.setHeader("Content-Dispostion", "attachment;filename="
     + new String(condition.getLoadname().getBytes(),
       "iso-8859-1"));
   FileInputStream fis = new FileInputStream(file);
   OutputStream ops = response.getOutputStream();
   byte[] b = new byte[1024];
   int real = fis.read(b);// 每次读取1024个字节
   while (real > 0) {
    ops.write(b, 0, real);
    real = fis.read(b);
   }
   ops.close();
   fis.close();
  }
  return null;
 }