接口多适用类（泛型）

    public class IC
    {
        public int Id { get; set; }
    }
    public class  test
    {
        public Bll bll=new Bll();
        public void YouMath()
        {
            var model = new IC();
            bll.Add(model);
        }

    }

    public class Bll : IBll
    {
        public void Delete(int id)
        {
            throw new NotImplementedException();
        }

        public void Add(IC model)
        {
            throw new NotImplementedException();
        }

        public void Update(IC model)
        {
            throw new NotImplementedException();
        }

        public void Get(int id)
        {
            throw new NotImplementedException();
        }

        public void GetModelsByPage(int currPage, int pageSize)
        {
            throw new NotImplementedException();
        }

        public void DoSomeThin()
        {
            throw new NotImplementedException();
        }
    }
    public interface IBll : IBaseBll<IC>
    {
        void DoSomeThin();
    }

    public interface IBaseBll<in T> where T : new()
    {
        void Delete(int id);
        void Add(T model);
        void Update(T model);
        void Get(int id);
        void GetModelsByPage(int currPage, int pageSize);
    }