11.2 观察者模式(Observer) ：java标准库

11.2 观察者模式(Observer) ：java标准库

package demo.spring.boot.demospringboot.ObserverModel;

import lombok.extern.slf4j.Slf4j;
import org.junit.Test;

import java.util.Observable;
import java.util.Observer;

@Slf4j
class StdObserverModel implements Observer {

    @Override
    public void update(Observable o, Object arg) {
        log.info("msg:{}", arg);
    }
}

class Subject extends Observable {
    /**
     * 必须要是change改变才会通知，所以要覆写
     */
    public synchronized void setChanged() {
        super.setChanged();
    }
}
public class StdObserver {

    @Test
    public void test() {
        Subject observable = new Subject();
        observable.addObserver(new StdObserverModel());
        observable.setChanged();
        observable.notifyObservers("xx");
        observable.setChanged();
        observable.notifyObservers("xx");
    }
}