步骤一:建立观察者接口
public interface Observer { public void update(); }
步骤二:建立具体观察者
public class Observer1 implements Observer { @Override public void update() { System.out.println("Observer1更新了"); } }
public class Observer2 implements Observer { @Override public void update() { System.out.println("Observer2更新了"); } }
步骤三:建立抽象被观察者角色
public interface Subject { public void add(Observer observer); public void delete(Observer observer); public void notifyObserver(); public void operator(); }
public abstract class AbstractSubject implements Subject { private Vector<Observer> vector=new Vector<Observer>(); @Override public void add(Observer observer) { vector.add(observer); } @Override public void delete(Observer observer) { vector.remove(observer); } @Override public void notifyObserver() { Enumeration<Observer> enumo=vector.elements(); while(enumo.hasMoreElements()) { enumo.nextElement().update(); } } }
步骤四:建立具体实现的被观察者
public class MySubject extends AbstractSubject{ @Override public void operator() { System.out.println("update self"); notifyObserver(); } }
步骤五:测试
public class Test { public static void main(String[] args) { Subject sub=new MySubject(); sub.add(new Observer1()); sub.add(new Observer2()); sub.operator(); } }