为枚举(enum)类型添加的备注属性，并且获取枚举的属性值

为枚举(enum)类型添加的备注属性，并且获取枚举的属性值

枚举类型（也称为枚举）是非常有意思的的一种值类型，它不仅可以提高程序的可读性，而且可以减少因业务改变而导致的程序改动。

另外枚举类型是强类型，接受方法必须有一个相同的匹配参数，否则将会出错。

好，废话少说，至于枚举类型(emun)的特性，几乎会编程的人都懂的，偶没功力在这里长篇大论。

下面是一个例子，偶还是按官方的写法，以星期为例子：

代码

    class Program
    {
        static void Main(string[] args)
        {

            Console.Write(GetDays(Days.Saturday));
            Console.Read();
        }

        static string GetDays(Days _days)
        {
            string d = string.Empty;
            switch (_days)
            {
                case Days.Monday: d = "Today is Monday."; break;
                case Days.Tuesday: d = "Today is Tuesday."; break;
                case Days.Wednesday: d = "Today is Wednesday."; break;
                case Days.Thursday: d = "Today is Thursday."; break;
                case Days.Friday: d = "Today is Friday."; break; ;
                case Days.Saturday: d = "Today is Saturday."; break;
                case Days.Sunday: d = "Today is Sunday."; break;
            }
            return d;
        }

    }

    public enum Days
    {
        /// <summary>
        /// this is sunday
        /// </summary>
        Sunday = 7,
        /// <summary>
        /// this is monday
        /// </summary>
        Monday = 1,
        /// <summary>
        /// this is tuesday
        /// </summary>
        Tuesday = 2,
        /// <summary>
        /// this is wednesday
        /// </summary>
        Wednesday = 3,
        /// <summary>
        /// this is thursday
        /// </summary>
        Thursday = 4,
        /// <summary>
        /// this is friday
        /// </summary>
        Friday = 5,
        /// <summary>
        /// this is saturday
        /// </summary>
        Saturday = 6
    };

很明显，"Today is Saturday." 当然是输出结果，可问题来了，这只是一个枚举，7条枚举值记录，假如，我要改成：hi ,cora ! this is saturday. 然后其他另外6条都不一样的，假设我们有100个或者更多这样的枚举值（只是里面的值）要更改，业务层方法GetDays这样的方法岂不是大改？（当然这只是假设，如果真实的话，或许会有更灵活的方式去处理）

晕了，小菜的又开始说BT了...

然后，我把程序稍稍改了一下，加了一个公共的类RemarkAttribute的类，然后加了一个remark的属性:

代码

    public class RemarkAttribute : Attribute
    {
        private string _remark;
        public RemarkAttribute(string _remark)
        {
            this._remark = _remark;
        }
        public string Remark
        {
            get { return _remark; }
            set { _remark = value; }
        }

        public static string GetEnumRemark(System.Enum _enum)
        {

            Type type = _enum.GetType();
            FieldInfo fd = type.GetField(_enum.ToString());
            if (fd == null) return string.Empty;
            object[] attrs = fd.GetCustomAttributes(typeof(RemarkAttribute), false);
            string name = string.Empty;
            foreach (RemarkAttribute attr in attrs)
            {
                name = attr.Remark;
            }
            return name;
        }
    }

然后把GetDays方法去掉，并且枚举加上一个属性并且加上一个属性值：

代码

    class Program
    {
        static void Main(string[] args)
        {

            Console.Write(RemarkAttribute.GetEnumRemark(Days.Wednesday));
            Console.Read();
        }

    }

    public enum Days
    {
        /// <summary>
        /// this is sunday
        /// </summary>
        [Remark("this is sunday")]
        Sunday = 7,
        /// <summary>
        /// this is monday
        /// </summary>
        [Remark("this is monday")]
        Monday = 1,
        /// <summary>
        /// this is tuesday
        /// </summary>
        [Remark("this is tuesday")]
        Tuesday = 2,
        /// <summary>
        /// this is wednesday
        /// </summary>
        /// 
        [Remark("this is wednesday")]
        Wednesday = 3,
        /// <summary>
        /// this is thursday
        /// </summary>
        [Remark("this is thursday")]
        Thursday = 4,
        /// <summary>
        /// this is friday
        /// </summary>
        [Remark("this is friday")]
        Friday = 5,
        /// <summary>
        /// this is saturday
        /// </summary>
        [Remark("this is saturday")]
        Saturday = 6
    };

好了，原来的业务处理方法GetDays可以省掉了，假设（偶好象比较喜欢假设），假设我们有100个或者更多个这样的枚举值要更改，那么我们只要把Remark的属性值改一下就可以了，业务层完全不用动（当然，连整个枚举都要更改的话，我就没办法喽）。

比较简单吧？个人而言还是比较喜欢简单而又不失经典的编码方式，或者园子里的朋友有更好的方式，不防提出来分享一下吧。