找了好久终于找到一个jsp上能用的…… 分享！！
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<link rel="stylesheet" href="../css/common.css" href="css/common.css" type="text/css" />
<title>管理区域</title>
<style type="text/css"><!--
#newPreview
{
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);
}
--></style>
<script type="text/javascript" language="javascript"><!--
var flag=true;
function PreviewImg(imgFile)
{
//新的预览代码，支持 IE6、IE7,IE8也支持，firefox不支持！！我测试了的……
var newPreview = document.getElementById("newPreview");
newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgFile.value;
if(flag)
{
newPreview.style.width = "100px";
newPreview.style.height = "80px";
}
}
function setImgWH()
{
var newPreview = document.getElementById("newPreview");
flag=false;
newPreview.style.width = document.getElementById("txtImgWidth").value;;
newPreview.style.height = document.getElementById("txtImgHeight").value;
}
// --></script>
</head>
<body>
<div id="man_zone">
<form action="product.do?command=addProduct" method="post" name="Upload" enctype="multipart/form-data">
<table width="100%" border="0" align="center" cellpadding="3"
cellspacing="1" class="table_style">
<tr>
<td class="left_title_2">
商品图片：
</td>
<td><input type="file" name="file" onchange="javascript:PreviewImg(this);" style="border: 1px #FFFFFF
solid;background:#efefef" style="border: 1px #FFFFFF
solid;background:#efefef" /><font color=red>*</font><div id="newPreview"></div></td>
</tr>
<tr>
<td class="left_title_1">
<input type="submit" name="Submit" value="增加" />
</td>
<td>
<input type="reset" name="Reset" value="重置" />
</td>
</tr>
</table>
</form>
</div>
</body>
</html>