ajax获取webservice返回值

$.ajax({
            url: "AJAXResponseForm.aspx",
            type: "post",
            dataType: "json",
            success: function(data, textStatus) {
            alert(data.city + " " + data.retCd + " " + data.retMsg);
            }
        });

Response.ContentType = "application/json; charset=utf-8";
Response.Write("{\"city\":\"局域网\",\"retCd\":\"0\",\"retMsg\":\"\"}");
Response.Flush();
Response.End();