56行代码理解RxJava

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自己动手实现RxJava。

最简单的观察者模式

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class Data {}

interface Subscriber {
    public void onEvent(Data d);
}

class Observable {
    private Subscriber subscriber;
    public void register(Subscriber s) {
        subscriber = s;
    }
    private void onEvent(Data d) {
        if(subscriber != null) {
            subscriber.onEvent(d);
        }
    }
}

多级观察者

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class InterSubscriber implements Subscriber {
    private Subscriber subscriber;
    
    public InterSubscriber register(Subscriber s) {
        subscriber = s;
    }
    @Override
    public void onEvent() {
        // 1. do something
        // 2. tell subscriber
        if(subscriber != null) {
                subscriber.onEvent();
        }
    }
}

Observable o = new Observable();
InterSubscriber is0 = new InterSubscriber();
InterSubscriber is1 = new InterSubscriber();
Subscriber s = new Subscriber();

o.register(is0);
is0.register(is1);
is1.register(s);
o.onEvent();

数据处理流程： o.onEvent() -> is0.onEvent() -> is1.onEvent() -> s.onEvent

中间观察者的另一面是被观察者

被观察者的行为可以总结为：

产生事件，事件