标签:blank update zookeeper user 并且 解决 介绍 print 页面
//主题接口 public interface Subject { void registerObserver(Observer observer); void removeObject(Observer observer); void notifyObservers(); } //主题具体实现类 public class ConcreteSubject implements Subject{ List<Observer> observers=new ArrayList<Observer>(); private int state; //注册观察者 @Override public void registerObserver(Observer observer) { observers.add(observer); } //移除观察者 @Override public void removeObject(Observer observer) { int index=observers.indexOf(observer); if(index>=0){ observers.remove(index); return; } } //通知观察者:类似消息推送 @Override public void notifyObservers() { for(Observer observer:observers){ observer.update(this); } } public int getState() { return state; } public void setState(int state) { this.state = state; notifyObservers(); } } //观察者接口 public interface Observer { void update(Subject subject); } //观察者实现类 public class ConcreteObserver implements Observer{ private int state; //同步主题的状态 @Override public void update(Subject subject) { this.state=((ConcreteSubject)subject).getState(); } public int getState() { return state; } public void setState(int state) { this.state = state; } } //客户端测试类 public class Client { public static void main(String[] args) { Subject subject=new ConcreteSubject(); ConcreteObserver observerA=new ConcreteObserver(); ConcreteObserver observerB=new ConcreteObserver(); subject.registerObserver(observerA); subject.registerObserver(observerB); ((ConcreteSubject)subject).setState(10); System.out.println("观察者A(订阅者A):"+observerA.getState()); System.out.println("观察者B(订阅者B):"+observerB.getState()); } } 运行结果: 观察者A(订阅者A):10 观察者B(订阅者B):10
//具体主题类(继承自主题类Observable) public class ConcreteSubject extends Observable{ private int state; public void setState(int state) { this.state = state; setChanged(); notifyObservers(); } public int getState() { return state; } } //具体观察者(实现javaAPI Observer) public class ConcreteObserver implements Observer{ private int state; @Override public void update(Observable o, Object arg) { this.state=((ConcreteSubject)o).getState(); } public int getState() { return state; } } //客户端 public class Client { public static void main(String[] args) { ConcreteSubject subject=new ConcreteSubject(); ConcreteObserver observerA=new ConcreteObserver(); ConcreteObserver observerB=new ConcreteObserver(); subject.addObserver(observerA); subject.addObserver(observerB); subject.setState(123); System.out.println("观察者A(订阅者A):"+observerA.getState()); System.out.println("观察者B(订阅者B):"+observerB.getState()); } } 运行结构: 观察者A(订阅者A):123 观察者B(订阅者B):123
作者:邱勇Aaron
出处:http://www.cnblogs.com/qiuyong/
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参考:Head First 设计模式
标签:blank update zookeeper user 并且 解决 介绍 print 页面
原文地址:http://www.cnblogs.com/qiuyong/p/7079973.html