C#基础---Attribute(标签） 和 reflect（反射) …

Person(Country=PersonCountry.UNKnown)]
    public class Person
    {
        public virtual void Eat()
        {
            Console.WriteLine("我们吃东西");
        }
    }

    [Person(Country=PersonCountry.USA)]
    public class USA : Person
    {
        public override void Eat()
        {
            Console.WriteLine("我们吃火鸡");
        }
    }


    [Person(Country=PersonCountry.China)]
    public class Chinese : Person
    {
        public override void Eat()
        {
            Console.WriteLine("我们吃汤圆");
        }
    }

    [Person(Country=PersonCountry.USA)]
    public class USA : Person
    {
        public override void Eat()
        {
            Console.WriteLine("我们吃火鸡");
        }
    }

    public class PersonAttribute:Attribute
    {
        private PersonCountry _country = PersonCountry.UNKnown;
        public PersonCountry Country
        {
            get
            {
                return _country;
            }
            set
            {
                this._country = value;
            }
        }

    }

    public enum PersonCountry
    {
        USA,
        China,
        Canada,
        UNKnown
    }

public class PersonHelper
    {
        public static Person GetPersonObj(PersonCountry contryType)
        {
            Assembly assembly = Assembly.GetExecutingAssembly();
            Type[] typeList = assembly.GetTypes();

            foreach (Type currentType in typeList)
            {                
                var attribute = (PersonAttribute)Attribute.GetCustomAttribute(currentType, typeof(PersonAttribute));

                if (attribute!=null && attribute.Country == contryType)
                {
                    return currentType.InvokeMember(null, BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.CreateInstance, null, null, new object[] { }) as Person;
                }                 
            }

            return new Person();
        }
    }

      public static void Main(string[] args)
        {
            Person p1 = PersonHelper.GetPersonObj(PersonCountry.China);
            p1.Eat(); //输出:我们吃汤圆
 
            Person p2 = PersonHelper.GetPersonObj(PersonCountry.Canada);
            p2.Eat(); //输出:我们吃意大利面
        }        

本博客描述的例子很牵强，不过只是感觉这种想法还是不错的。方便项目的扩展。希望对大家有用。同时也是自己为了回顾一下反射和打标签的用法，才打算写这篇博客的。