Observable和Observer

Observable和Observer

前一段时间看了一下Observable和Observer的事件框架，觉的还不错，先记下来

 

Observer接口和Observable类可用于Model-View模式中：当Model中的数据发生变化时，Model主动通知View此变化。
其中Model用Observable类来实现，而View可以用实现了Observer接口的类来实现。举例如下

 

import java.util.Observable; import java.util.Observer; /** * @author * 观察员 *  */ public class Human implements Observer { private String name; public Human() { super(); } public Human(String name) { super(); this.name = name; } public void update(Observable o, Object arg) { //获取被观察对象当前的状态 System.out.println(((InvalidMan)o).getState()); //向当前观察者通知消息 System.out.println(name + arg); } }

import java.util.Observable; /** * 被观察者 **/ public class InvalidMan extends Observable { private int state; //差 public final static int STATE_BAD = 0; //死 public final static int STATE_DEAD = -1; //良好 public final static int STATE_FINE = 1; public InvalidMan() { super(); } public InvalidMan(int state) { this.state = state; } public int getState() { return state; } public void setState(int state) { this.state = state; } public void changeState(int state){ if(this.state != state) { this.state = state; this.setChanged(); if(STATE_BAD == state || STATE_DEAD == state) { this.notifyObservers("...危险..."); } else if(STATE_FINE == state) { this.notifyObservers("...准备出院..."); } } else { this.notifyObservers("...老样子..."); } } }

 

测试DEMO

import java.util.Observer; public class ObserverDemo { public ObserverDemo() { } public static void main(String[] args) { //被观察者 InvalidMan o1 = new InvalidMan(InvalidMan.STATE_BAD); //观察员 Observer oo1 = new Human("医生"); //观察员 Observer oo2 = new Human("护士"); //观察员 Observer oo3 = new Human("家人"); //向被观察对象注册观察员 //为病人注册 观察员：医生，护士，家人 o1.addObserver(oo1); o1.addObserver(oo2); o1.addObserver(oo3); //更改被观察对象的状态 o1.changeState(InvalidMan.STATE_DEAD); o1.changeState(InvalidMan.STATE_BAD); o1.changeState(InvalidMan.STATE_FINE); } }