基于iframe的无刷新上传文件，并返回上传结果

<!-- 将target配置成一个隐藏的iframe -->
<form id= "form1" enctype ="multipart/form-data" action= "/FileDownload/register.do?type=upload" method ="post" target= "hframe">
     附件： <input type ="file" name="path"/>< br/>
     <input type ="submit" value="确定"/>
     <iframe name ="hframe" id="hframe" style=" display: none" ></iframe >
</form>

//后台的代码中调用父窗口的js函数，回写结果
out.write("<script type='text/javascript'>parent.callback('123')</script>" );