通过 Activator.CreateInstance 以及  继承关系实现

    public interface Name
    {
        String GetName();
    }

    public class Join : Name
    {
        public string GetName()
        {
            return "Join";
        }
    }

    public class Thomas : Name
    {
        public string GetName()
        {
            return "Thomas";
        }
    }

    public class RecongisePerson
    {
        Hashtable nameTable = new Hashtable();
        public void SetNameList(String name, Type type)
        {
            nameTable[name] = type;
        }

        public String GetName(String person)
        {
            Name b = (Name)Activator.CreateInstance((Type)nameTable[person]);
            String s = b.GetName();
            return s;
        }
    }