玩转Java设计模式之观察者模式

发布时间：2023-04-26 13:35:06 所属栏目：教程来源：

导读：//抽象主题
@Data
public abstract class Subject {
//主题订阅者们
private List<Observer> observerList = Lists.newArrayList();
//订阅
public void register(Observer observer) {

//抽象主题
@Data
public abstract class Subject {
//主题订阅者们
private List<Observer> observerList = Lists.newArrayList();
//订阅
public void register(Observer observer) {
observerList.add(observer);
}
//取消订阅
public void remove(Observer observer) {
observerList.remove(observer);
}
//发布东西
public abstract void publish(String msg);
}
//抽象观察者
@Slf4j
@Data
@AllArgsConstructor
public abstract class Observer {
//观察者名称
private String name;
//更新状态，由主题调度
public void update(Object subject, Object args) {
log.info("{}获取到变更通知：{}", name, args);
}
}
//博客主题
@Slf4j
public class Blog extends Subject {
@Override
public void publish(String msg) {
log.info("发布msg:{}", msg);
//通知订阅者
getobserverList().forEach(observer -> observer.update(this, msg));
}
}
//普通用户观察者
@Slf4j
public class normalObserver extends Observer {
public normalObserver(String name) {
super(name);
}
@Override
public void update(Object subject, Object args) {
super.update(subject, args);
log.info("{}获取到变更通知：普通用户可以不缓存", getName());
}
}
//vip用户观察者
@Slf4j
public class VipObserver extends Observer {
public VipObserver(String name) {
super(name);
}
@Override
public void update(Object subject, Object args) {
super.update(subject, args);
log.info("{}获取到变更通知：vip可以缓存", getName());
}
}
@Slf4j
public class Application {
public static void main(String[] args) {
Blog blog = new Blog();
VipObserver wang = new VipObserver("老王99");
VipObserver lee = new VipObserver("老李");
normalObserver four = new normalObserver("小四");
normalObserver twoegg = new normalObserver("二蛋");
log.info("---------------------begin--------------------");
// 用户订阅博客，普通和vip用户
new Thread(() -> {
blog.register(wang);
sleep(2);
blog.register(lee);
sleep(2);
blog.register(four);
}).start();
// 博客线程每隔2秒发布一次文章, 总共发布4次
new Thread(() -> {
IntStream.rangeClosed(1, 4).forEach(i -> {
blog.publish(String.format("新把戏第%s次", i));
sleep(2);
});
}).start();
// 有用户退出订阅博客，也有二蛋加入订阅
new Thread(() -> {
sleep(3);
blog.remove(lee);
sleep(2);
blog.register(twoegg);
}).start();
}
private static void sleep(int seconds) {
try {
TimeUnit.SECONDS.sleep(seconds);
} catch (InterruptedException e) {
log.error("error : ", e);
}
}
}
折腾Java设计模式之观察者模式

jdk内置的Obverser和Observable

@Slf4j
public class ObserverApplication {
public static void main(String[] args) {
log.info("Enter Text: ");
EventSource eventSource = new EventSource();
eventSource.addobserver((obj, arg) -> {
log.info("Received response: {}", arg);
});
eventSource.addobserver((obj, arg) -> {
log.info("Received response2: {},,{}", arg, obj
);
});
new Thread(eventSource).start();
}
}
class EventSource extends Observable implements Runnable {
public void run() {
while (true) {
String response = new Scanner(system.in).next();
setChanged();
notifyObservers(response);
}
}
}

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