JS上定义上传按钮：
new Ext.Button({
 text : '上传',
 iconCls : 'uploadIcon',
 handler : function() {
  var url = top.rootPath
    + "/public/extjs/mycomp/fileupload/upload.ou?method=uploadfile&linkId=-1";
  var dialog = new Ext.ux.UploadDialog.Dialog({
   id : 'uploadComp',
   url : url,
   title : '文件上传__上传过程中关闭窗口，不影响上传',
   width : 450,
   height : 300,
   minWidth : 450,
   minHeight : 300,
   draggable : true,
   resizable : true,
   autoCreate : true,
   constraintoviewport : true,
   modal : true,
   post_var_name : 'mms',
   reset_on_hide : false,
   allow_close_on_upload : true, // 关闭上传窗口是否仍然上传文件
   upload_autostart : true
    // 是否自动上传文件
   })

  dialog.show();
  //dialog.on('uploadsuccess', successfunc);

 }

后台上传功能实现：

private void uploadfile(HttpServletRequest request,
        HttpServletResponse response){
      try {
      String json ="";
      String linkId = request.getParameter("linkId");
      if(linkId!=null && !linkId.equals("")){
    DiskFileItemFactory fac = new DiskFileItemFactory();
    ServletFileUpload upload = new ServletFileUpload(fac);
    List fileList = upload.parseRequest(request);
    Iterator iter = fileList.iterator();
    while(iter.hasNext()){
      FileItem fileItem = (FileItem)iter.next();
      if(!fileItem.isFormField()){
       String name = fileItem.getName();
                String fileSize = new Long(fileItem.getSize()).toString();
                if(name == null || name.equals("") || fileSize.equals("0"))
                       continue;
           
                String fileName = name.substring(name.lastIndexOf("\\")+1);
                   //存储文件
                String suffix = name.substring(name.lastIndexOf(".")+1);
                String uuid = UUID.randomUUID().toString();
               // File saveFile = new File("d:\\upload\\"+uuid+"."+suffix);
              
                String staffId = LoginParams.getLoginStaff().getStaffId();
                String fileType = getFileType(suffix);
             
               
                //保存文件
                FileSystem hdfs = TThdfsHelper.getFileSystem();
 
          // 上传文件到HDFS集群
           String path = TThdfsHelper.getFullPath("flowForm/2013/"+uuid+"."+suffix);
           InputStream input =  fileItem.getInputStream();
          //InputStream input = fileItem; // 输入流，根据实际需要处理
           ActionResult uploadresult = hdfs.writeFile(path, input, true, true);
           TThdfsHelper.close(hdfs);
          
                FileVO fileVo = new FileVO();
                fileVo.setFileName(fileName);
                fileVo.setFileSize(fileSize);
                fileVo.setSuffix(suffix);
                fileVo.setUUID(uuid);
                fileVo.setFileType(fileType);
                fileVo.setStaffId(staffId);
                fileVo.setLinkId(linkId);
                int result = (Integer)BOCallProxy.executeBO("com.redsea.file.bo.FileBO",
                       "uploadFile", new Object[]{fileVo});
                if(uploadresult.getCode().equals(ActionResult.SUCCESS)){
                 json ="{'success':true,'message':'上传成功'}" ;
                }else{
                 json ="{'success':false,'message':'上传失败'}" ;
                }
              
                
 
      }
     
    }
     JspUtil.writerPrint(response, json);
     }else{
        json ="{success:false,message:'缺少组件编码'}";
        JspUtil.writerPrint(response, json);
     }
  // JspUtil.writerJsonPrint(response, json);
   
   
  } catch (FileUploadException e) {
   e.printStackTrace();
  } catch (Exception e) {
   e.printStackTrace();
  }
       
 }