网址http://jingyan.baidu.com/article/215817f78370dd1edb142372.html
<body>
<table width="100%" border="0" cellspacing="0" cellpadding="0">
<tbody>
<tr>
<td height="101" align="center">
<div id="localImag" style="border: 1px solid red;">
<img id="preview" src="" width="100" height="100" style="display: block;border: 1px solid blue;" />
</div>
</td>
</tr>
<tr>
<td align="center" style="padding-top:10px;">
<form method="get" action="xznetwork" name="textfile">
<input type="file" name="file" id="doc" multiple="multiple" style="150px;" onchange="javascript:setImagePreview();">
</form>
</td>
</tr>
</tbody>
</table>
</body>
<script type="text/javascript">
//下面用于图片上传预览功能
function setImagePreview(avalue) {
//input
var docObj = document.getElementById("doc");
//img
var imgObjPreview = document.getElementById("preview");
//div
var divs = document.getElementById("localImag");
if (docObj.files && docObj.files[0]) {
//火狐下，直接设img属性
imgObjPreview.style.display = 'block';
imgObjPreview.style.width = '100px';
imgObjPreview.style.height = '100px';
//imgObjPreview.src = docObj.files[0].getAsDataURL();
//火狐7以上版本不能用上面的getAsDataURL()方式获取，需要一下方式
imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);
} else {
//IE下，使用滤镜
docObj.select();
var imgSrc = document.selection.createRange().text;
var localImagId = document.getElementById("localImag");
//必须设置初始大小
localImagId.style.width = "100px";
localImagId.style.height = "100px";
//图片异常的捕捉，防止用户修改后缀来伪造图片
try {
localImagId.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
localImagId.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
} catch(e) {
alert("您上传的图片格式不正确，请重新选择!");
return false;
}
imgObjPreview.style.display = 'none';
document.selection.empty();
}
return true;
}
</script>