Ashx登录

  <script type="text/javascript">
        window.onload = function () {
            var url = document.getElementById("url");
            url.onclick = function () {
                var src = document.getElementById("imgCode").src;           //函数用于使用当地时间返回当前Date对象中的毫秒值
                document.getElementById("imgCode").src = src+"?d="+new Date().getMilliseconds();
            };
        }
    </script>在body 里面做提交表单
 <form method="post" action="Login.ashx">
       用户名: <input type="text" name="txtName" /><br />
        密码:<input type="password" name="txtPwd" /><br />
        验证码:<input type="text" name="txtCode" /> <a href="javascript:void(0)" rel="external nofollow"  id="url"><img src="ValidateCode.ashx" id="imgCode" /></a>    </form>

//这里做验证

public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = “text/plain”;
Common.ValidateCode validateCode = new Common.ValidateCode();
string code=validateCode.CreateValidateCode(4);
validateCode.CreateValidateGraphic(code, context);
}

+一个验证码的封装helper14.1108