struts 让浏览器提示文件下载，而不是显示文件的内容

<action name="Download" class="xx.action.DownLoad">
<result type="stream" name="success">
<param name="inputName">inputStream</param>
<param name="contentType">application/octet-stream</param>
<param name="contentDisposition">attachment;filename="xx.jpg"</param>
</result>
</action>

@Results(
{
@Result(name = "qcCode", type = "stream", params={"contentType", "application/octet-stream","contentDisposition","attachment;filename=qcCode.png","inputName","inputStream"})
})