比较好的直接导出服务器文件的JS

  <SCRIPT type="text/javascript">
     function downloadFile(url)
{  
try{
var elemIF = document.createElement("iframe");  
elemIF.src=url;  
elemIF.style.display = "none";  
document.body.appendChild(elemIF);  
}catch(e){

}
} 
     </SCRIPT>

<span style="margin-bottom: 10px;cursor:pointer;" onclick="downloadFile('jsp/risk/model.xls');">&nbsp;&nbsp;导出模版</span>&nbsp;&nbsp;