準備階段：

　　定義介面和實現介面的類。

    interface IMyInterface
    {
        void Write();
    }

    /// <summary>
    /// 實現類1
    /// </summary>
    public class MyTest1 : IMyInterface
    {
        public MyTest1()
        {
            var methodNames = GetType().GetMethods().Select(m => m.Name).ToList();
        }

        
 
public void Write()
        {
            Console.WriteLine("這裡是測試類 1");
        }
    }

    /// <summary>
    /// 實現類2
    /// </summary>
    public class MyTest2 : IMyInterface
    {
        public void Write()
        {
            Console.WriteLine("這裡是測試類 2");
        }

        
 
public void MyMethod2()
        {
            Console.WriteLine("這裡是測試類2 的第2個方法");
        }
    }

定義執行方法（最後是呼叫）

        /// <summary>
        /// 獲取實現了某介面的類
        /// </summary>
        /// <param name="iType"></param>
        public static void GetClasses(Type iType) 
        {
            
 
var types = AppDomain.CurrentDomain.GetAssemblies().SelectMany(a => a.GetTypes()).Where(t => t.GetInterfaces().Contains(iType)).ToList();

            foreach(var t in types)
            {
                Console.WriteLine(t.FullName);
                Type tt = Type.GetType(t.FullName);
                IMyInterface my = Activator.CreateInstance(tt) as IMyInterface;　　//這裡不應該把介面直接寫進來的
                my.Write();

                var methodNames = tt.GetMethods().Select(m => m.Name).ToList();
                Console.WriteLine("該類具有的方法名：");
                List<string> oriNames = new List<string> { "ToString", "Equals", "GetHashCode", "GetType" };
                methodNames = methodNames.Except(oriNames).ToList();

                //但問題是你不知道方法名對應的功能是什麼啊！！！
                foreach (var name in methodNames)
                {
                    Console.WriteLine("  " + name);
                }
                Console.WriteLine();
            }
        }

呼叫：

            GetClasses(typeof(IMyInterface));
            Console.ReadKey();