spring MVC 导出excel ExcelMVCSpringEXTAjax

   // 导出excel方法
    @RequestMapping("exportExcel")
    public void exportExcel(HttpServletRequest request, HttpServletResponse response)
    {
        HttpSession session = request.getSession();
        session.setAttribute("state", null);
        // 生成提示信息，
        response.setContentType("application/vnd.ms-excel");
        String codedFileName = null;
        OutputStream fOut = null;
        try
        {
            // 进行转码，使其支持中文文件名
            codedFileName = java.net.URLEncoder.encode("中文", "UTF-8");
            response.setHeader("content-disposition", "attachment;filename=" + codedFileName + ".xls");
            // response.addHeader("Content-Disposition", "attachment;   filename=" + codedFileName + ".xls");
            // 产生工作簿对象
            HSSFWorkbook workbook = new HSSFWorkbook();
            //产生工作表对象
            HSSFSheet sheet = workbook.createSheet();
            for (int i = 0; i <= 30000; i++)
            {
                HSSFRow row = sheet.createRow((int)i);//创建一行
                HSSFCell cell = row.createCell((int)0);//创建一列
                cell.setCellType(HSSFCell.CELL_TYPE_STRING);
                cell.setCellValue("测试成功" + i);
            }
            fOut = response.getOutputStream();
            workbook.write(fOut);
        }
        catch (UnsupportedEncodingException e1)
        {}
        catch (Exception e)
        {}
        finally
        {
            try
            {
                fOut.flush();
                fOut.close();
            }
            catch (IOException e)
            {}
            session.setAttribute("state", "open");
        }
        System.out.println("文件生成...");
    }
    @RequestMapping("check")
    public void check(HttpServletRequest request, HttpServletResponse response)
    {
        try
        {
            if ("open".equals(request.getSession().getAttribute("state")))
            {
                request.getSession().setAttribute("state", null);
                response.getWriter().write("true");
                response.getWriter().flush();
            }
            else
            {
                response.getWriter().write("false");
                response.getWriter().flush();
            }
        }
        catch (IOException e)
        {}
    }

/***********导出start************/
	var excel_flag = 0;
	var win_check;
    var exportExcelBtn = new Ext.Button({
        renderTo:'exportExcelBtn',
        text:"<span class='marL10'>"+'导出'+"</span>",
        height:24,
        iconCls:'findnew',
        width:110,
        bodyStyle:'padding:5px',
        handler: function()
        {
            excel_flag = 0;
            //禁用按钮
        	exportExcelBtn.disable();
        	location.href = "exportExcel";
        	//每隔一秒向后台发送请求
        	win_check = window.setInterval(check, 1000);  
        }
    });
    
    /**
     * 用于防止重复提交
     */
    function check()
    {
    	excel_flag ++;
    	if(excel_flag > 30)
    	{
    		//清空定时器
    		window.clearInterval(win_check);
    		//启用按钮
    		exportExcelBtn.enable();
    	}
    	Ext.Ajax.request(
        	{
            	url : 'check',
            	success : function (response, result)
            	{
            		if(response.responseText=="true")
            		{
            			//清空定时器
            			window.clearInterval(win_check);
            			//启用按钮
            			exportExcelBtn.enable();
            		}
            	}
        	})
    }
    /***********导出end*****************/