Alternatives to Reflection

I would like to implement my own Universal Binary JSON Specification-like specification. As one of my first steps I would like to have a method, which takes an object as parameter, like Gson does in its String com.google.gson.Gson.toJson(Object src) method. So I would like to know the fields and the data types of them. As far as I know does Gson use reflection to achieve that.

Another "solution" could be Serialization. But it's maybe tough to extract the fields from there, and I would prefer anyway, that it's not a must for the object to implement Serializable.

Is Reflection the way to go with my intentions?