JQuery跨域调用webservice有关问题

页面JS代码如下：方法一：$.getJSON(    "http://ip地址/chatService/chatService.asmx/userLogin?jsoncallback=?",    {userId:"'"+$("#userId").val()+"'", serverId:"'"+$("#serverId").val()+"'", date:"'"+new Date()+"'"},    function(json)    {       if(json.length > 0)       {           alert(json);                            }       }); 方法二：               $.ajax({                    async: false，                    type: "POST",                    contentType:"application/json;utf-8",                    url: "http://ip地址/chatService/chatService.asmx/userLogin?callback=?",                    data: "{userId:'"+$("#userId").val()+"', serverId:'"+$("#serverId").val()+"', date:'"+ new Date() +"'}",                    datatype:"json",                    success: function(json){                        if(json != "")                        {                            alert(json);                        }                    }                });

web service方法已经包含了[System.Web.Script.Services.ScriptService]        [WebMethod]        public void userLogin(string userId, string serverId, string date)        {            DBManager db = new DBManager("COM");            SqlParameter[] p = new SqlParameter[4];            p[0] = new SqlParameter("@userId", SqlDbType.Int, 0);            p[0].Direction = ParameterDirection.Input;            p[0].Value = userId;            p[1] = new SqlParameter("@serverId", SqlDbType.Int, 0);            p[1].Direction = ParameterDirection.Input;            p[1].Value = serverId;            p[2] = new SqlParameter("@date", SqlDbType.DateTime, 0);            p[2].Direction = ParameterDirection.Input;            p[2].Value = date;            p[3] = new SqlParameter("@returns", SqlDbType.Int, 0);            p[3].Direction = ParameterDirection.ReturnValue;            int sysId = db.ExeProc("ap_webUserLog", p);            string callback = HttpContext.Current.Request["jsoncallback"];            string retV = "";            retV += "({state:" + sysId + ", msg:'成功建立连接'})";            HttpResponse response = HttpContext.Current.Response;            response.Write(callback + retV);            response.End();        }