Observer模式初探

去印客面试，dlee问了下Observer模式，我知道Observer是什么，也用过java.util.Observable和java.util.Observer，回来后再看看Observer是怎么实现的，写了个小例子，简单的思考了下Observer

 

public class Test {
	public static void main(String[] args) {
		MyObserver myor = new MyObserver();
		MyObservable myoe = new MyObservable(myor);
		myoe.setData(1);
		myoe.setData(2);
		myoe.setData(3);
	}
}

class MyObservable {
	private boolean isChanged;
	private int data;
	private MyObserver mo;

	public MyObservable(MyObserver mo) {
		this.mo = mo;
	}

	private void setChanged() {
		isChanged = true;
	}

	public int getData() {
		return data;
	}

	public void setData(int data) {
		this.data = data;
		setChanged();
		notifyObservers();
	}

	public void notifyObservers() {
		if (isChanged == true) {
			mo.update(this);
		}
		isChanged = false;
	}

}

class MyObserver {
	public void update(MyObservable mo) {
		System.out.println("data is changed to " + mo.getData());
	}
}

Observerable依赖Observer接口,观察模式是OCP原则的一个很好的例子

原本模糊的概念，现在清晰很多了，谢谢