ASP.NET上传图片时，产生预览

<tr bgcolor="#f5f5f5">
     <td height="30" align="center" valign="middle">图片链接</td>
     <td height="35" align="center" valign="middle"><input type="file" name="uploadfile1" runat="server" id="uploadfile1" onpropertychange="document.all.imgID.src='file:///'+this.value">  
     </td>
    </tr>
    <tr bgcolor="#f5f5f5">
     <td height="70" align="center" valign="middle">缩略图</td>
     <td height="70" align="center" valign="middle"><img id="imgID" width="82" height="65" border="0" > 
     </td>
    </tr>