<div id="form_box">
<form action="UploadServlet" method="post" οnsubmit="return checkMyFiles()" enctype="multipart/form-data">
<div class="up_div">
<input type="file" name="upfile" class="file_input" multiple="multiple">
</div>
<br/>
<input type="submit" value="上传" id="sub">
</form>
<script type="text/javascript">
function checkMyFiles(form){
alert("1");
return false;
}
</script>
</div>
上面是有两个方法的 可以执行