02 观察者模式

基于util包的观察者模式demo

import java.util.Observable;
import java.util.Observer;
/**
 * @author by yze on 2019/4/19
 * @see
 * @since
 */
public class ObserverTest {
    static class WeatherData extends Observable {
        private int arg1;
        private int arg2;

        public WeatherData(int arg1, int arg2) {
            this.arg1 = arg1;
            this.arg2 = arg2;
        }

        public void setMeasurements(int arg1, int arg2) {
            this.arg1 = arg1;
            this.arg2 = arg2;
            measureDataChanged();
        }

        public void measureDataChanged() {
            setChanged();
            notifyObservers();
        }

        public int getArg1() {
            return arg1;
        }

        public void setArg1(int arg1) {
            this.arg1 = arg1;
        }

        public int getArg2() {
            return arg2;
        }

        public void setArg2(int arg2) {
            this.arg2 = arg2;
        }
    }


    static class Observer1 implements Observer {
        private Observable observable;

        public Observer1(Observable observable) {
            this.observable = observable;
            observable.addObserver(this);
        }

        @Override
        public void update(Observable obs, Object arg) {
            if (obs instanceof WeatherData) {
                System.out.println(((WeatherData) obs).getArg1() + " " + ((WeatherData) obs).getArg2());
            }
        }
    }


    static class Observer2 implements Observer {
        private Observable observable;

        public Observer2(Observable observable) {
            this.observable = observable;
            observable.addObserver(this);
        }

        @Override
        public void update(Observable obs, Object arg) {
            if (obs instanceof WeatherData) {
                System.out.println("this is observer 2 :" + ((WeatherData) obs).getArg1() + " " + ((WeatherData) obs).getArg2());
            }
        }
    }

    public static void main(String[] args) {
        WeatherData weatherData = new WeatherData(1, 2);
        Observer1 observer1 = new Observer1(weatherData);
        Observer2 observer2 = new Observer2(weatherData);
        weatherData.setMeasurements(3, 4);
    }
}