class AttributeTest
 {
        public void Test()
        {
            Type type = typeof(UseAttribute);
            object[] customAttributes = type.GetCustomAttributes(true);
            foreach (object customAttribute in customAttributes)
            {
                DefindAttribute defindAttribute = customAttribute as DefindAttribute;
                if (defindAttribute != null)
                {
                    Console.WriteLine(defindAttribute.ShowInfo);
                }
            }
        }
    }

    [Defind("这是第一个特性的创建！")]   //是DefindAttribute的特性后面的Attribute就不需要了
    class UseAttribute
    {
         //do nothing;
    }

    #region 创建特性，要是继承Attribute特性，其实特性也就是一个类
    class DefindAttribute :Attribute
    {
        public DefindAttribute(string showInfo)
        {
            ShowInfo = showInfo;
        }
        public string ShowInfo { get; set; }
    }
    #endregion

在主函数中进行实例化并调用

static void Main(string[] args)
 {
      AttributeTest attributeTest = new AttributeTest();
      attributeTest.Test();
      Console.ReadKey();
 }