###问题描述
实现一个观察者模式，监听方法接受一个Integer参数，并且其打印出来
###自己实现
public static void main(String[] args) {
EventSource eventSource = new EventSource();
eventSource.register(new Listener());
eventSource.print(1);
}
interface Print {
void print(Integer integer);
}
static class EventSource implements Print {
private Set<Print> listeners = Sets.newCopyOnWriteArraySet();
public void print(Integer integer) {
for (Print listener : listeners) {
listener.print(integer);
}
}
public void register(Print print) {
listeners.add(print);
}
}
static class Listener implements Print {
public void print(Integer integer) {
System.out.println(integer);
}
}
###使用JDK实现
public static void main(String[] args) {
EventSource eventSource = new EventSource();
eventSource.addObserver(new Listener());
eventSource.print(1);
}
static class EventSource extends Observable {
public void print(Integer integer) {
setChanged();
notifyObservers(integer);
}
}
static class Listener implements Observer {
public void update(Observable o, Object arg) {
System.out.println(arg);
}
}
###使用Guava
public static void main(String[] args) {
EventBus eventBus = new EventBus();
eventBus.register(new Listener());
eventBus.post(1);
}
static class Listener {
@Subscribe
public void print(Integer integer) {
System.out.println(integer);
}
}
