设计模式-策略模式

什么是策略模式：策略模式定义算法簇分别封装起来，并使它们之间可以相互替换，该模式让算法的变化独立于调用者之外。
定义比较抽象，还是用代码来说明，我们可以定义一组行为接口，然后针对接口做不同的实现，最后通过调用不同的行为实现达到不同的效果，比方说狗吃骨头，但是玩具狗什么都不吃。

public abstract class Animal {

    private EatAction eatAction;

    private RunAction runAction;

    public abstract void performRun();

    public abstract void performEat();

    public EatAction getEatAction() {
        return eatAction;
    }

    public void setEatAction(EatAction eatAction) {
        this.eatAction = eatAction;
    }

    public RunAction getRunAction() {
        return runAction;
    }

    public void setRunAction(RunAction runAction) {
        this.runAction = runAction;
    }
}

public interface EatAction {

    public void eat();
}

public interface RunAction {

    public void run();
}

public class DogEat implements EatAction {

    @Override
    public void eat() {
        System.out.println("Eat Bone");
    }
}

public class DogRun implements RunAction {
    @Override
    public void run() {
        System.out.println("run with Four legs");
    }
}

public class ToyDogEat implements EatAction {
    @Override
    public void eat() {
        System.out.println("eat nothing");
    }
}

public class Main {


    public static void main(String[] args){
        Animal dog = new Dog();
        dog.setEatAction(new DogEat());
        dog.setRunAction(new DogRun());
        dog.performEat();
        dog.performRun();

        dog.setEatAction(new ToyDogEat());
        dog.performEat();

    }
}