桥接模式的正确理解

Question

Am I correctly undestand Bridge Pattern:

BEFORE:

  public class Main2 {
            @SuppressWarnings("unused")
            public static void main(String[] args) {
                Car car11 = new BadNativeCar();
                Car car12 = new GoodNativeCar();
                Car car21 = new BadForeignCar();
                Car car22 = new GoodForeignCar();
            }
        }

        interface Car{
            public void drive();
            public void stop();
        }

        class NativeCar implements Car{
            @Override
            public void drive() {
            }
            @Override
            public void stop() {
            }
        }

        class ForeignCar implements Car{
            @Override
            public void drive() {
            }
            @Override
            public void stop() {
            }
        }

        class GoodNativeCar extends NativeCar{
        }
        class BadNativeCar extends NativeCar{
        }
        class GoodForeignCar extends ForeignCar{
        }
        class BadForeignCar extends ForeignCar{
        }

桥接之后:

 public class Main2 {
        public static void main(String[] args) {
            BadCar badCar = new BadCar();
            GoodCar goodCar = new GoodCar();
            CarAbstraction car11 = new NativeCar(badCar);
            CarAbstraction car12 = new NativeCar(goodCar);
            CarAbstraction car21 = new ForeignCar(badCar);
            CarAbstraction car22 = new ForeignCar(goodCar);
        }
    }

    interface CarAbstraction{
        public void drive();
        public void stop();
    }

    //Abstraction
    abstract class CarAbstractionImpl implements CarAbstraction{
        private CarImplementor carImplementor;

        public CarAbstractionImpl(CarImplementor carImplementor) {
            this.carImplementor = carImplementor;
        }

        @Override
        public void drive() {
            carImplementor.drive();
        }
        @Override
        public void stop() {
            carImplementor.stop();
        }
    }

    //RefinedAbstraction1
    class NativeCar extends CarAbstractionImpl{
        public NativeCar(CarImplementor carImplementor) {
            super(carImplementor);
        }
    }
    //RefinedAbstraction2
    class ForeignCar extends CarAbstractionImpl{
        public ForeignCar(CarImplementor carImplementor) {
            super(carImplementor);
        }
    }



    //Implementor
    interface CarImplementor extends CarAbstraction{
    }

    //ConcreteImplementor1
    class GoodCar implements CarImplementor{
        @Override
        public void drive() {
        }
        @Override
        public void stop() {
        }
    }

    //ConcreteImplementor2
    class BadCar implements CarImplementor{
        @Override
        public void drive() {
        }
        @Override
        public void stop() {
        }
    }

- drifter

---

这个问题有什么问题吗？ - drifter

Answer 1

从您的问题中，我得到了以下类图： 之前：

                    ________Car_________
                    /                    \
               NativeCar              ForeignCar
               /       \              /        \
   GoodNativeCar   BadNativeCar GoodForeignCar  BadForeignCar

之后：

            CarAbstraction
                 |
         CarAbstractionImpl-------------HAS-A-------> CarImplementor
          /             \                              /          \
     NativeCar       ForeignCar                    GoodCar       BadCar

如果我们查看桥接模式的类图http://www.oodesign.com/bridge-pattern.html, 它看起来像是桥接模式。然而，CarAbstraction--CarAbstractionImpl的类层次结构可以省略。这意味着CarAbstraction HAS A CarImplementor，NativeCar和ForeignCar将被CarAbstraction继承。

因此，从类图中看，它看起来像是桥接模式。

但是概念上呢？NativeCar和ForeignCar是抽象还是也可以用作实现？它们能否与GoodCar和BadCar交换？这个事实也需要考虑。如果NativeCar和ForeignCar是抽象的，而GoodCar和BadCar是实现的，那么这就是针对这种情况的桥接模式。

- doptimusprime

Answer 2

据我理解，您试图做类似于以下的事情：

 When:

        A
     /     \
    Aa      Ab
   / \     /  \
 Aa1 Aa2  Ab1 Ab2

Refactor to:

     A         N
  /     \     / \
Aa(N) Ab(N)  1   2

（从这里得到的：何时使用桥接模式？它与适配器模式有何不同？）

我对桥接模式不是很熟悉，但它看起来是正确的。

- user1074896