IE 6及8 预览图片

<style type="text/css">
        #preview_div
        {
            /* 该对象用于在IE下显示预览图片 */
            filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);
        }

</style>

<script type="text/javascript">
        function setImg(fup) {
            var temp = fup.value.toLowerCase();
            temp = temp.substr(temp.length - 4);

            if (temp != ".jpg") {
                alert("格式错误");
                return false;
            }
            var ua = navigator.userAgent.toLowerCase();
            var preview_div = document.getElementById("preview_div");
            var preview_img = document.getElementById("preview_img");

            var ver = ua.substr(ua.indexOf("msie") + 5, 1);
            if (ver > 6) {
                preview_div.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = fup.value;
                preview_img.style.display = 'none';
            }
            else {
                preview_img.src = fup.value;
            }
        }
</script>

//省略的表单元素，以下是关键代码

<div id="preview_div" class="size" style="float:left;">
    <img id="preview_img" alt="图书封面" height="120" src="../../Images/default.jpg" class="size" />
</div>
<div style="float:left;margin-left:5px;  padding-top:98px">
    <asp:FileUpload ID="FileUpload1" runat="server" onchange="setImg(this)" />
</div>