C#通过反射实例化对象

     public static IPDFProvider Get(string vt)
        {
            IPDFProvider r = null;
            Type tt = Type.GetType(vt);
            ConstructorInfo ci = tt.GetConstructor(System.Type.EmptyTypes);
            r = ci.Invoke(null) as IPDFProvider;
            return r;
        }

        public static IPDFProvider Get(string path,string vt)
        {
            System.Reflection.Assembly ass = System.Reflection.Assembly.LoadFile(path);
            //string vt = "Laptop.Order.PDF.WABPdfProvider2";
            Laptop.Order.PDF.IPDFProvider r = null;
            Type tt = ass.GetType(vt);
            ConstructorInfo ci = tt.GetConstructor(System.Type.EmptyTypes);
            r = ci.Invoke(null) as Laptop.Order.PDF.IPDFProvider;
            return r;
        }