关于使用SmartUpload实现文件下载的问题

JSP代码：
<%@ page contentType="text/html; charset=gb2312"%>
<%@ include file="../common/scmValidSession.jsp"%>
<jsp:useBean id="myBean" class="com.sscm.order.nodeorder.NodeOrderExport"></jsp:useBean>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<link rel="stylesheet" href="../ScmStyle.css" type="text/css">
<%
myBean.getParameters(request);
myBean.getLoginInfo(request);

String act = request.getParameter("act");
if("query".equals(act)) {
myBean.query();
}
try{
if("unload".equals(act)){
myBean.unload(request,pageContext);
} 
}catch(Exception e){
e.printStackTrace();
}
%>
<title>导出网点订单</title>
<script language="javascript" src="../common/commonMethod.js"></script>
<script type="text/javascript" src="../common/cal2.js"language="javascript"></script>
<script> 
function doUnload(){
if (document.frmData.filename.value == "") {
alert("请输入导出文件名！")
return;
}
document.frmData.action="order_export.jsp?act=unload";
document.frmData.submit();
}
function doQuery(){
document.frmData.action="order_export.jsp?act=query";
document.frmData.submit();
}
</script>
</head><body  >
<table align="center">
  <tr>
    <td valign="middle"><img src="../images/z02.gif" width="30" height="38" border="0"></td>
    <td>&nbsp;导出网点订单</td>
  </tr>
</table>
<form action="order_export.jsp" method="post" name="frmData">
<table width="100%" border="1" cellpadding="1" cellspacing="4" class="tableStyle">
<tr>
<td align="right" width="15%">发货日期：</td>
<td width="25%" align="left">
<input type="text" name="deliverDate" value="<%=myBean.getDeliverDate()%>" readonly>
<img src="../images/cal.gif" width="16" height="16" style="border:0; cursor:pointer " onClick="showCal('deliverDate');"> </td>
<td align="right" width="15%">导出文件：</td>
<td align="left" width="35%">
<input type="text" name="filename" value="<%=myBean.getFileName()%>" >
</td>
</tr>
<tr>
<td colspan="4" align="center">
<input type="hidden" name="txtKaCode" value="HL">
<input type="button" class="button" value="查 询" onClick="doQuery();">&nbsp;&nbsp;&nbsp;&nbsp;
<input id="unloadfile" name="unloadfile" type="button" class="button" value="导 出" onClick="doUnload();">
</td>
</tr> 
</table>
</form>
</html>