属性注入

public interface ITimeProvider

    {

        DateTime CurrentDate { get; }

    }



    public class TimeProvider : ITimeProvider

    {

        public DateTime CurrentDate { get { return DateTime.Now; } }

    }

    public class Assembler

    {

        static Dictionary<Type, Type> dictionary = new Dictionary<Type, Type>();

        static Assembler()

        {

            dictionary.Add(typeof(ITimeProvider), typeof(TimeProvider));

        }



        public object Creat(Type type)

        {

            if ((type == null) || !dictionary.ContainsKey(type))

                throw new NullReferenceException();

            return Activator.CreateInstance(dictionary[type]);

        }



        //泛型方式调用

        public T Creat<T>()

        {

            return (T)Creat(typeof(T));

        }

    }

自定义特性

[AttributeUsage(AttributeTargets.Class,AllowMultiple=true)]

    sealed class DecoratorAttribute : Attribute

    {

        public readonly object injector;

        readonly Type type;

        public DecoratorAttribute(Type type)

        {

            if (type == null) throw new ArgumentNullException("type");

            this.type = type;

            injector = (new Assembler()).Creat(this.type);

        }

        public Type Type { get { return this.type; } }

    }

对Assembler再包装

 static class AttributeHelper

    {

        public static T Injector<T>(object target) where T:class

        {

            if (target == null) throw new ArgumentNullException("target");

            return (T)(((DecoratorAttribute[])target.GetType().GetCustomAttributes(typeof(DecoratorAttribute), false))

                .Where(x => x.Type == typeof(T))

                .FirstOrDefault()

                .injector);

        }

    }

实体类

 [Decorator(typeof(ITimeProvider))]

    class Client

    {

        public int GetYear()

        {

            var provider = AttributeHelper.Injector<ITimeProvider>(this);

            return provider.CurrentDate.Year;

        }

    }

 

看看调用

        /// <summary>

        ///GetYear 的测试

        ///</summary>

        [TestMethod()]

        public void GetYearTest()

        {

            Client target = new Client(); // TODO: 初始化为适当的值

            target.GetType();

        }

这里有点模糊，我自己手动打出来这个段代码并且测试通过，但是却不懂在什么场合去应用他，后面我会把自己做过的几个软件从新按照设计模式规划下，到时如果用到会对这里做个说明，现在先朦朦胧胧的放在这里，待后续