1.定義

策略模式：定義了算法族，分別封裝起來，讓她們可以相互替換。讓算法的變化獨立于使用算法的客體

2.介紹

應用于一件事有多種行為（算法），采用此模式使得系統能夠非常靈活。

3.類圖

image.png

4.實例

package designMode;

import java.io.IOException;

/**
 * 策略模式：定義了算法族，分別封裝起來，讓她們可以相互替換。讓算法的變化獨立于使用算法的客體
 */
public class StrategyPattern {
    public static void main(String[] args) throws IOException {
        Animal bird = new Bird(new BirdMove(),new BirdSound());
        Animal bird1 = new Bird();
        Animal fish = new Fish(new FishMove(),new FishSound());
        bird.performMove();
        bird.performSound();
        bird.commonbehavior();
        bird1.performMove();
        bird1.performSound();
        bird1.commonbehavior();
        fish.commonbehavior();
        fish.performSound();
        fish.performMove();
    }
    //抽出公共屬性
    static class Animal{
        //提出變化部分，封裝算法實現，針對接口編程
        private SoundBehavior soundBehavior;
        private MoveBehavior moveBehavior;
        public void performSound(){
            soundBehavior.sound();
        }
        public void performMove(){
            moveBehavior.move();
        }
        public void commonbehavior(){
            System.out.println("公共行為：吃飯睡覺打豆豆！");
        }
        public void setSoundBehavior(SoundBehavior soundBehavior) {
            this.soundBehavior = soundBehavior;
        }
        public void setMoveBehavior(MoveBehavior moveBehavior) {
            this.moveBehavior = moveBehavior;
        }
    }
    static class Bird extends Animal{
        //對具體實現進行編程不夠靈活
        public Bird() {
            super.moveBehavior=new BirdMove();
            super.soundBehavior=new BirdSound();
        }

        //不對具體類編程,在運行時通過多態指定行為實現類
        public Bird(MoveBehavior moveBehavior,SoundBehavior soundBehavior) {
            super.setMoveBehavior(moveBehavior);
            super.setSoundBehavior(soundBehavior);
        }
    }
    static class Fish extends Animal{
        public Fish() {
            super.moveBehavior=new FishMove();
            super.soundBehavior=new FishSound();
        }
        public Fish(MoveBehavior moveBehavior,SoundBehavior soundBehavior){
            super.setMoveBehavior(moveBehavior);
            super.setSoundBehavior(soundBehavior);
        }
    }
    //針對行為的方法族
    interface SoundBehavior{
        void sound();
    }
    public static class BirdSound implements SoundBehavior{
        @Override
        public void sound() {
            System.out.println("bird sound：嘰嘰喳喳");
        }
    }
    public static  class FishSound implements SoundBehavior{
        @Override
        public void sound() {
            System.out.println("fish sound:咕嚕咕嚕");
        }
    }
    interface MoveBehavior{
        void move();
    }
    public static  class FishMove implements MoveBehavior{
        @Override
        public void move() {
            System.out.println("fish move:swim");
        }
    }
    public static class BirdMove implements MoveBehavior{
        @Override
        public void move() {
            System.out.println("bird move：fly");
        }
    }
}