软件设计之适配器模式

类模式

我们知道插座的电压为交流电220V，而日常电器使用的是直流电且电压会较小，比如手机充电会通过插头适配器达到额定的输入电流。下面我们实现这个案例：将220V电压转化为5V的电压。

 

package Adapter.Class;public class Adapter extends Power220V implements Power5V {@Overridepublic int output5V() {int input = output220V();int output = input/44;return output;}
}

package Adapter.Class;public class Client {public static void main(String[] args) {Phone phone = new HuaWei();phone.charging(new Adapter());}
}

package Adapter.Class;public class HuaWei implements Phone{@Overridepublic void charging(Adapter adapter) {System.out.println("华为手机适配电压5伏");if(adapter.output5V()==5) System.out.println("华为手机充电成功");else System.out.println("华为手机充电不成功");}
}

package Adapter.Class;public interface Phone {public void charging(Adapter adapter);
}

package Adapter.Class;public interface Power5V {public int output5V();
}

package Adapter.Class;public class Power220V {private int power = 220;public int output220V() {System.out.println("电压" + power + "伏");return power;}
}

这种模式被称作类模式，可以看到Adapter继承了Adaptee(要适配者）并且实现了Target(要适配者）。对于一对一的适配还有一种模式叫对象模式，在这种模式下，Adaptee会作为Adapter的成员属性而不是让Adapter去继承Adaptee。

对象模式 

 

package Adapter.Object;public class Adapter implements Power5V {Power220V power220V;public Adapter() {}public Adapter(Power220V power220V) {this.power220V = power220V;}@Overridepublic int output5V() {int input = power220V.output220V();int output = input/44;return output;}
}

package Adapter.Object;public class Client {public static void main(String[] args) {Phone phone = new HuaWei();phone.charging(new Adapter(new Power220V()));}
}

 

双向模式

上面的案例介绍了一对一的适配，还有一种适配是双向的。下面用一个案例介绍：实现猫学狗叫和狗学猫抓老鼠。

package Adapter.BothWay;public class Adapter implements CatImpl,DogImpl{private CatImpl cat;private DogImpl dog;public CatImpl getCat() {return cat;}public void setCat(CatImpl cat) {this.cat = cat;}public DogImpl getDog() {return dog;}public void setDog(DogImpl dog) {this.dog = dog;}@Overridepublic void catchMice() {System.out.print("狗学");cat.catchMice();}@Overridepublic void cry() {System.out.print("猫学");dog.cry();}
}

package Adapter.BothWay;public class Cat implements CatImpl{@Overridepublic void catchMice() {System.out.println("猫抓老鼠");}@Overridepublic void cry() {}
}

package Adapter.BothWay;public interface CatImpl {public void catchMice();public void cry();
}

package Adapter.BothWay;public class Dog implements DogImpl{@Overridepublic void cry() {System.out.println("狗叫");}@Overridepublic void catchMice() {}
}

package Adapter.BothWay;public interface DogImpl {public void cry();public void catchMice();
}

package Adapter.BothWay;public class Client {public static void main(String[] args) {Adapter adapter = new Adapter();CatImpl cat = new Cat();DogImpl dog = new Dog();adapter.setCat(cat);adapter.setDog(dog);cat = (CatImpl) adapter;cat.cry();dog = (DogImpl) adapter;dog.catchMice();}
}