Head First 策略模式

1、算法接口類及實現

public interface FlyBehavior {
    public void fly();
}

public interface QuackBehavior {
    public void quack();
}

 

public class FlyNoWay implements FlyBehavior{
    public void fly() {
        System.out.println("I can't fly");
    }
}

public class FlyWithWings implements FlyBehavior{
    public void fly() {
        System.out.println("I'm flying");
    }
}

 

public class Quack implements QuackBehavior{
    public void quack() {
        System.out.println("Quack");
    }
}


public class Squeak implements QuackBehavior{
    public void quack() {
        System.out.println("Squeak");
    }
}

public class MuteQuack implements QuackBehavior {
    public void quack() {
        System.out.println("<< Silence >>");
    }
}

 

2、抽象類及具體實現類

public abstract class Duck {

    //爲行爲接口類型聲明兩個引用變量，全部的鴨子類都繼承它們
    FlyBehavior flyBehavior;
    QuackBehavior quackBehavior;

    public Duck(){

    }

    public abstract void display();

    //委託給行爲類
    public void performFly(){
        flyBehavior.fly();
    }
    public void performQuack(){
        quackBehavior.quack();
    }

    public void swim(){
        System.out.println("All ducks float, even decoys!");
    }

    //動態設定行爲
    public void setFlyBehavior(FlyBehavior fb){
        flyBehavior = fb;
    }
    public void setQuackBehavior(QuackBehavior qb){
        quackBehavior = qb;
    }

}

 

public class MallardDuck extends Duck {

    public MallardDuck(){
        //根據需求選擇行爲
        quackBehavior = new Quack();
        flyBehavior = new FlyWithWings();
    }

    public void display() {
        System.out.println("I'm a real Mallard duck");
    }
}

 

3、測試類

public class MinDuckSimulator {

    public static void main(String[] args){
        Duck mallard = new MallardDuck();
        mallard.performQuack();
        mallard.performFly();
    }

}

 

 4、類圖

 

 

Head First設計模式讀書總結——策略模式

LOL設計模式之「策略模式」