java设计模式-观察者模式

本质就是有很多哥们看着一个哥们，这哥们发生了个啥动作，看着他的哥们就要执行对应的动作。 和责任链模式很像但是它不能往回穿，应用的地方到处都是，spring的refresh方法里就有。 首先定义个观察者接口

public interface MyObserve {
    void action(MyEvent myEvent);
}

定义两个实体：

public class Cat implements MyObserve {
    @Override
    public void action(MyEvent myEvent) {
        System.out.println("猫猫捕鱼"+myEvent.getTime()+"小时");
    }
}

public class Dog implements MyObserve {
    @Override
    public void action(MyEvent myEvent) {
        System.out.println("狗狗散步"+myEvent.getTime()+"小时");
    }
}

定义个事件类：

public class MyEvent {
    private Long time;
    private Weather weather;

    public MyEvent(){

    }

    public MyEvent(Long time, Weather weather) {
        this.time = time;
        this.weather = weather;
    }

    public Long getTime() {
        return time;
    }

    public void setTime(Long time) {
        this.time = time;
    }

    public Weather getWeather() {
        return weather;
    }

    public void setWeather(Weather weather) {
        this.weather = weather;
    }
}

定义个被观察者：

public class Weather {
    private boolean fine = false;
    private List<MyObserve> observes = new ArrayList<>();

    public Weather addObserve(MyObserve observe){
        observes.add(observe);
        return this;
    }

    public boolean isFine(){
        return fine;
    }

    public void fineWeather(){
        fine = true;
        for (MyObserve observe : observes) {
            observe.action(new MyEvent(5L,this));
        }
    }
}

执行：

public class Test1 {
    public static void main(String[] args) {
        Weather weather = new Weather();
        weather.addObserve(new Dog()).addObserve(new Cat());
        weather.fineWeather();
    }
}