jquery执行具体的方法

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js" type="text/javascript"></script>    <script type="text/javascript">        $(document).ready(function() {            $.ajax({                type: "POST",                contentType: "application/json",                url: "JqueryDemo.aspx/GetUserName",                data: "{}",                dataType: "json",                success: dd,                error: function(x, e) {                 alert("e")                }            });        });        function dd(result) {            alert(result.d)         }    </script>

//[webmethod(enablesession = true)]//或[webmethod(true)]        [WebMethod]        public static string GetUserName()        {            return "234";        }