设计模式--observer（316）

模式原型:

实例：

public interface Observer {
    public abstract void update(NumberGenerator numberGenerator);
}

public abstract class NumberGenerator {
    private ArrayList observers = new ArrayList();

    public void addObserver(Observer observer) {
        observers.add(observer);
    }

    public void deleteObserver(Observer observer) {
        observers.remove(observer);
    }

    public void notifyObservers() {
        Iterator iterator = observers.iterator();
        while (iterator.hasNext()) {
            Observer ob = (Observer) iterator.next();
            ob.update(this);
        }
    }

    public abstract int getNumber();//获取数值

    public abstract void execute(); //生成数值
}

public class RandomNumberGenerator extends NumberGenerator{

    private Random random = new Random();
    private int number;

    @Override
    public int getNumber() {
        return number;
    }

    @Override
    public void execute() {
        for(int i = 0;i < 10; i++){
            number = random.nextInt(60);
            notifyObservers();
        }
    }
}

public class GraphObserver implements Observer {
    @Override
    public void update(NumberGenerator numberGenerator) {
        System.out.println("GraphObserver");
        for (int i = 0; i < numberGenerator.getNumber(); i++) {
            System.out.print("*");
        }
        System.out.println();
        try {
            Thread.sleep(100);
        } catch (Exception e) {

        }
    }
}

public class DigitObserver implements Observer {
    @Override
    public void update(NumberGenerator numberGenerator) {
        System.out.println("DigitObserver:" + numberGenerator.getNumber());
        try {
            Thread.sleep(100);
        } catch (Exception e) {

        }
    }
}

public class Main {
    public static void main(String[] args) {
        NumberGenerator generator = new RandomNumberGenerator();
        generator.addObserver(new DigitObserver());
        generator.addObserver(new GraphObserver());
        generator.execute();
    }
}

结果：

DigitObserver:22
GraphObserver
**********************
DigitObserver:47
GraphObserver
***********************************************
DigitObserver:12
GraphObserver
************
DigitObserver:44
GraphObserver
********************************************
DigitObserver:48
GraphObserver
************************************************
DigitObserver:3
GraphObserver
***
DigitObserver:45
GraphObserver
*********************************************
DigitObserver:0