桥接模式：将抽象与实现分离，实现面向接口编程。

场景：面向接口编程，例如，三层架构中的DAL与BLL的引用可以使用桥接模式实现，修改DAL时，BLL中的逻辑不需要改变

UML图：

示例代码：

public interface IBaseDAL    {        void Insert();    }

public class UserDAL:IBaseDAL    {        public void Insert()        {            Console.WriteLine("插入User");        }    }

public class MenuDAL:IBaseDAL    {        public void Insert()        {            Console.WriteLine("插入Menu");        }    }

public interface IBaseBLL    {        IBaseDAL baseDal { get; set; }        void SetCurrentDal(IBaseDAL BaseDal);        void InsertOne();    }

public class UserBLL : IBaseBLL    {        public UserBLL(IBaseDAL BaseDal)        {            SetCurrentDal(BaseDal);        }        public IBaseDAL baseDal { get; set; }        public void SetCurrentDal(IBaseDAL BaseDal)        {            this.baseDal = BaseDal;        }        public void InsertOne()        {            baseDal.Insert();        }    }

public class MenuBLL:IBaseBLL    {        public MenuBLL(IBaseDAL BaseDal)        {            this.baseDal = BaseDal;        }        public IBaseDAL baseDal { get; set; }        public void SetCurrentDal(IBaseDAL BaseDal)        {            this.baseDal = BaseDal;        }        public void InsertOne()        {            this.baseDal.Insert();        }    }

class Program    {        static void Main(string[] args)        {            IBaseBLL user = new UserBLL(new UserDAL());            user.InsertOne();            IBaseBLL menu = new MenuBLL(new MenuDAL());            menu.InsertOne();        }    }