<script type="text/javascript">

function setImagePreview() {

var docObj = document.getElementById("ctl00_ContentMain_file_head");

var fileName = docObj.value;

if (!fileName.match(/.jpg|.gif|.png|.bmp/i)) {

alert('您上传的图片格式不对。请又一次选择！');

return false;

} 

var imgObjPreview = document.getElementById("preview");

if (docObj.files && docObj.files[0]) {

//火狐下，直接设img属性

imgObjPreview.style.display = 'block';

imgObjPreview.style.width = '63px';

imgObjPreview.style.height = '63px';

//imgObjPreview.src = docObj.files[0].getAsDataURL();

if (window.navigator.userAgent.indexOf("Chrome") >= 1 || window.navigator.userAgent.indexOf("Safari") >= 1) {

imgObjPreview.src = window.webkitURL.createObjectURL(docObj.files[0]);

}

else {

imgObjPreview.src = window.URL.createObjectURL(docObj.files[0]);

}

} else {

//IE下。使用滤镜

docObj.select();

docObj.blur();

var imgSrc = document.selection.createRange().text;

var localImagId = document.getElementById("localImag");

//必须设置初始大小

localImagId.style.width = "63px";

localImagId.style.height = "63px";

//图片异常的捕捉，防止用户改动后缀来伪造图片

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对。请又一次选择！

");

return false;

}

imgObjPreview.style.display = 'none';

document.selection.empty();

}

return true;

} 

</script> 

<div id="localImag"><img id="preview" width="-1" height="-1" style="display:none" /></div> 

<asp:FileUpload ID="file_head" runat="server" onchange="javascript:setImagePreview();" />