动机:
当一个对象有了两个变化的维度,如何应对这种“多维度的变化”?如何利用面向对象技术来使得这个对象类型可以轻松沿着多个方向变化,而不引入额外的复杂度?
意图:
将抽象部分与实现部分分离,使它们都可以独立地变化。
出自:《设计模式》GoF
Bridge模式的几个要点:
1、Bridge模式使用“对象间的组合关系”解耦了抽象和实现之间固有的绑定关系,使得抽象(Tank的型号)和实现(不现的平台)可以沿着各处的维度来变化。
2、所谓抽象和实现沿着各处纬度的变化,即“子类化”它们,比如不同的Tank型号子类,和不同的平台子类。得到各个子类之后,便可以任意组它们,从而获得不同平台上的不同型号。
3、Bridge模式有时候类似于多继承方案,但是多继承方案往往违背单一职责原则(即一个类只有一个变化的原因),复用性比较差。Bridge模式是比多方案更好的解决方法。
4、Bridge模式的应用一般在“两个非常强的变化维庶,有时候即使有两个变化的维度,但是某个方向的变化维度并不剧烈,换言之两个不会导致纵横交错的结果,并不一定要使用Bridge模式。
稳定部分:
public abstract class Tank
{
protected TankPlatFormImplementation tankImpl;
public Tank(TankPlatFormImplementation tankImpl)
{
this.TankImpl = tankImpl;
}
public TankPlatFormImplementation TankImpl
{
get
{
return this.tankImpl;
}
set
{
this.tankImpl = value;
}
}
public abstract void Shot();
public abstract void Run();
public abstract void Stop();
}
public abstract class TankPlatFormImplementation
{
public abstract void MoveTankTo(Point to);
public abstract void DrawTank();
public abstract void DoShot();
}
{
protected TankPlatFormImplementation tankImpl;
public Tank(TankPlatFormImplementation tankImpl)
{
this.TankImpl = tankImpl;
}
public TankPlatFormImplementation TankImpl
{
get
{
return this.tankImpl;
}
set
{
this.tankImpl = value;
}
}
public abstract void Shot();
public abstract void Run();
public abstract void Stop();
}
public abstract class TankPlatFormImplementation
{
public abstract void MoveTankTo(Point to);
public abstract void DrawTank();
public abstract void DoShot();
}
变化部分:
//型号维度的变化
public class T50 : Tank
{
public T50(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
}
public override void Shot()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
public class T75 : Tank
{
public T75(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Shot()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
public class T90 : Tank
{
public T90(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Shot()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
//平台维度的变化
public class PCTankImplementation : TankPlatFormImplementation
{
public override void MoveTankTo(Point to)
{
}
public override void DrawTank()
{
}
public override void DoShot()
{
}
}
public class MobileTankImplementation : TankPlatFormImplementation
{
public override void MoveTankTo(Point to)
{
}
public override void DrawTank()
{
}
public override void DoShot()
{
}
}
public class T50 : Tank
{
public T50(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
}
public override void Shot()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T50
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
public class T75 : Tank
{
public T75(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Shot()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T75
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
public class T90 : Tank
{
public T90(TankPlatFormImplementation tankImpl) : base(tankImpl)
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Shot()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Run()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
public override void Stop()
{
//T90
TankImpl.DrawTank();
TankImpl.DoShot();
TankImpl.MoveTankTo(to);
}
}
//平台维度的变化
public class PCTankImplementation : TankPlatFormImplementation
{
public override void MoveTankTo(Point to)
{
}
public override void DrawTank()
{
}
public override void DoShot()
{
}
}
public class MobileTankImplementation : TankPlatFormImplementation
{
public override void MoveTankTo(Point to)
{
}
public override void DrawTank()
{
}
public override void DoShot()
{
}
}
主程序:
//用于多个维度变化的对象
public static void Main()
{
//变化点
//Mobile T50 的组合
TankPlatFormImplementation TankImpl = new MobileTankImplementation();
T50 tank = new T50(TankImpl);
//PC T90 的组合
TankPlatFormImplementation TankImpl = new PCTankImplementation();
T90 tank = new T90(TankImpl);
}
public static void Main()
{
//变化点
//Mobile T50 的组合
TankPlatFormImplementation TankImpl = new MobileTankImplementation();
T50 tank = new T50(TankImpl);
//PC T90 的组合
TankPlatFormImplementation TankImpl = new PCTankImplementation();
T90 tank = new T90(TankImpl);
}