java设计模式（六）策略模式

　　适用于同一操作的不同行为，策略模式定义了一系列的算法，并将每一个算法封装起来，而且使它们可以相互替换，让算法独立于使用它的客户而独立变化，具体应用场景如第三方支付对接不同银行的算法。

　　要点：1）抽象策略角色

　　　　    2）具体策略角色：包装相关算法和行为

　　　　　3）环境角色：持有一个策略类的引用，最终给客户端调用

1、抽象策略接口

public interface SwimmingStratege {
    public void swimming();
}

2、具体策略角色SwimmingWithFoot

public class SwimmingWithFoot implements SwimmingStratege {
    public void swimming() {
        System.out.println("我借助脚滑动在水中游走");
    }
}

3、具体策略角色SwimmingWithWind

public class SwimmingWithWind implements SwimmingStratege {
    public void swimming() {
        System.out.println("我借助风在水中游走");
    }
}

4、环境角色Duck 抽象类

public abstract class Duck {

    public void quack() {
        System.out.println("嘎嘎嘎");
    }

    public abstract void display();

    private SwimmingStratege swimmingStratege;

    public void setSwimmingStratege(SwimmingStratege swimmingStratege) {
        this.swimmingStratege = swimmingStratege;
    }

    public void swimming() {
        swimmingStratege.swimming();
    }
}

5、环境角色RealDuck

public class RealDuck extends Duck {

    public RealDuck() {
        super();
        super.setSwimmingStratege(new SwimmingWithFoot());
    }

    @Override
    public void quack() {
        super.quack();
    }

    public void display() {
        System.out.println("我是真的鸭子");
    }
}

6、环境角色

public class YellowDuck extends Duck {

    public YellowDuck() {
        super();
        super.setSwimmingStratege(new SwimmingWithWind());
    }

    @Override
    public void quack() {
        super.quack();
    }

    public void display() {
        System.out.println("我是大黄鸭");
    }

}

7、测试

public class Model {

    public static void main(String[] args) {
        Duck duck = new RealDuck();
//        Duck duck = new YellowDuck();
        duck.display();
        duck.quack();
        duck.swimming();
    }

}