策略模式

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策略模式

定义了算法族，分别封装起来，让他们之间可以相互替换，此模式让算法的变化独立于使用算法的客户。

Java实现

模拟鸭子应用，不同鸭子有不同的行为

策略接口及实现

飞行行为

接口

public interface FlyBehavior {

    void fly();
}

不同实现

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

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

public class FlyRocketPowered implements FlyBehavior {
    @Override
    public void fly() {
        System.out.println("I'm flying with a rocket!");
    }
}

鸭子类

抽象类

@Setter
public abstract class Duck {
    private FlyBehavior flyBehavior;

    public Duck() {
    }

    public abstract void display();

    public void performFly() {
        flyBehavior.fly();
    }

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

}

具体子类

public class ModelDuck extends Duck {
    public ModelDuck() {
        setFlyBehavior(new FlyNoWay());
    }

    @Override
    public void display() {
        System.out.println("I'm a model duck");
    }
}

测试

测试类

public class TestModelDuck {
    @Test
    public void test() {
        Duck model = new ModelDuck();
        model.performFly();
        model.setFlyBehavior(new FlyRocketPowered());
        model.performFly();
    }
}

测试结果

I can't fly
I'm flying with a rocket!

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