C# JObject 的使用生成json字符串

JObject obj = new JObject();            JObject obj1 = new JObject();            obj["where"] = obj1;            obj1["exname"] = "name";//{"exname": "name"}            obj["skip"] = 0;            obj["limit"] = 24;            obj["include"] = new JArray() { "a", "b" };// "include": ["a","b"]            if (!string.IsNullOrWhiteSpace("keyword"))            {                JObject obj2 = new JObject();                obj1["fileName"] = obj2;                obj2["like"] = "keyword";            }            //至此obj1的值为{"exname": "name","fileName": {"like": "keyword"}}            obj["order"] = "heatCount desc";            string json = obj.ToString();