验证码 更换的问题
我写一个验证码   更换的问题
这样就没有办法更换
<img   id= "Img1 "   onclick= "this.src=this.src "   alt= "看不清的话,点击更新 "   style= "cursor:hand;   "   src= "/ValidateKey.aspx "     width= "60 "   height= "20 "   border= "0 "   />


下面这个点击后就可以更换
                <img   id= "ValidateKye "   onclick= "this.src=this.src+ '1 ' "   alt= "看不清的话,点击更新 "   style= "cursor:hand;   "   src= "/ValidateKey.aspx?id=1 "     width= "60 "   height= "20 "   border= "0 "   />

是不是有一个缓存的问题,导致上面那个换不的呢.
请指教我下.....

------解决方案--------------------
Response.Buffer = true;
Response.ExpiresAbsolute = System.DateTime.Now.AddSeconds(-1);
Response.Expires = 0;
Response.CacheControl = "no-cache ";
Response.AppendHeader( "Pragma ", "No-Cache ");

------解决方案--------------------
<asp:TextBox ID= "CheckCode " runat= "server " Width= "85px "> </asp:TextBox> <a href= "javascript:loadimage(); "> <asp:Image id= "Image1 " runat= "server " ImageUrl= "Validate.aspx "> </asp:Image> </a>

<script type= "text/javascript " language= "JavaScript ">
<!--
function loadimage(){
document.getElementById( "Image1 ").src = "Validate.aspx? "+Math.random();
}
//-->
</script>