關(guān)于策略模式下需要用到一個接口多個實現(xiàn)的方案

http://www.reibang.com/p/0753de68244c

此鏈接是策略模式的案例家妆，講述多個優(yōu)惠策略實現(xiàn)同一個接口的應(yīng)用場景

我們需要用到DI的高級玩法：

在接口定義方法標識

優(yōu)惠策略接口抽象出一個方法Get() 獲取優(yōu)惠舔哪，優(yōu)惠的實現(xiàn)有很多挖滤，我們需要在Startup注入所有的優(yōu)惠策略的實現(xiàn)

    public interface IActivitiesStrategy
    {
        string Realize { get; }
        /// <summary>
        /// 獲取則扣策略
        /// </summary>
        /// <returns></returns>
        double GetDiscountStrategy();
    }

在優(yōu)惠策略的具體實現(xiàn)上寫出方法標識

    public class DoubleElevenActivities : IActivitiesStrategy
    {
        public string Realize => "雙十一優(yōu)惠";

        public double GetDiscountStrategy()
        {
            return 0.11;
        }
    }

    public class DoubleTwelveActivities : IActivitiesStrategy
    {
        public string Realize => "雙十二優(yōu)惠";

        public double GetDiscountStrategy()
        {
            return 0.12;
        }
    }

注冊所有方法

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IActivitiesStrategy, DoubleElevenActivities>();
            services.AddTransient<IActivitiesStrategy, DoubleTwelveActivities>();
            services.AddMvc();
        }

在使用時候判斷使用什么策略

    public class ValuesController : ControllerBase
    {
        private readonly IEnumerable<IActivitiesStrategy> _activitiesStrategy;

        public ValuesController(IEnumerable<IActivitiesStrategy> activitiesStrategy)
        {
            _activitiesStrategy = activitiesStrategy;
        }

        
        // GET api/values
        [HttpGet]
        public ActionResult<double> Get(string tag)
        {
            var method = _activitiesStrategy.Where(x => x.Realize == tag).FirstOrDefault();

            if (method != null)
            {
                return method.GetDiscountStrategy();
            }

            return 1;
        }
    }