asp.net 点击刷新按钮，只刷新验证码，不刷新整个页面

<asp:textbox runat="server" id="txtValueCode" class="yzm2"></asp:textbox><asp:Image ID="ImgCode" runat="server" Height="22px" ImageUrl="/ValidateCode1.aspx" Width="65px" class="yztp" />

<a href="javascript:fGetCode()"" class="refresh2">刷新</a>对应的刷新按钮

js里面写这样一个方法即可

function fGetCode() {

document.getElementById("ContentPlaceHolder1_ImgCode").src = "/ValidateCode1.aspx?" + Math.random();

}