效果如下：
实现代码：
JS脚本如下：
<
script language
=
"
javascript
"
type
=
"
text/javascript
"
>
function
getFullPath(obj)
{
if
(obj)
{
//
ie
if
(window.navigator.userAgent.indexOf(
"
MSIE
"
)
>=
1
)
{
obj.select();
return
document.selection.createRange().text;
}
//
firefox
else
if
(window.navigator.userAgent.indexOf(
"
Firefox
"
)
>=
1
)
{
if
(obj.files)
{
return
obj.files.item(
0
).getAsDataURL();
}
return
obj.value;
}
return
obj.value;
}
}
function yulan()
{
filename=document.getElementById('UpFile').value;
var fileText =filename.substring(filename.lastIndexOf("."),filename.length); //获取文件扩展名
var filePath =getFullPath(document.getElementById('UpFile'));
var fileName =fileText.toLowerCase();
if
((fileName!='.jpg')&&(fileName!='.gif')&&(fileName!='.jpeg')&&(fileName!='.png')&&(fileName!='.bmp'))
{
alert("对不起，系统仅支持标准格式的照片，请您调整格式后重新上传，谢谢 ！");
document.form1.UpFile.focus();
}
else
{
document.getElementById("preview").innerHTML="<img src='"+filePath+"' width=120 style='border:6px double #ccc'>";
}
}
<
/
script>
ASPX页面代码：
<
input
type
="file"
id
="UpFile"
class
="stylebtn"
name
="UpFile"
onchange
="yulan()"
/>
;
<
asp:Button
ID
="btnUpload"
runat
="server"
Text
="上 传"
onclick
="btnUpload_Click"
Height
="22px"
CssClass
="stylebtn"
/>
<
div
id
="preview"
></
div
>