RxBus.java

package com.anthony.library.data;

import rx.Observable;
import rx.subjects.PublishSubject;
import rx.subjects.SerializedSubject;
import rx.subjects.Subject;

/**
 * Created by Anthony on 2016/5/23.
 * Class Note:
 * use RxJava to implement EventBus
 * (Sticky event @see{http://reactivex.io/documentation/subject.html})
 */
public class RxBus {

    private static volatile RxBus defaultInstance;
    // 主题
    private final Subject<Object, Object> bus;

    // PublishSubject只会把在订阅发生的时间点之后来自原始Observable的数据发射给观察者
    public RxBus() {
        bus = new SerializedSubject<>(PublishSubject.create());
    }

    // 单例RxBus
    public static RxBus getDefault() {
        RxBus rxBus = defaultInstance;
        if (defaultInstance == null) {
            synchronized (RxBus.class) {
                rxBus = defaultInstance;
                if (defaultInstance == null) {
                    rxBus = new RxBus();
                    defaultInstance = rxBus;
                }
            }
        }
        return rxBus;
    }
    // 提供了一个新的事件
    public void post (Object content) {
        bus.onNext(content);
    }

    // 根据传递的 eventType 类型返回特定类型(eventType)的 被观察者
    public <T> Observable<T> toObserverable (Class<T> eventType) {
        return bus.ofType(eventType);
//        ofType = filter + cast
//        return bus.filter(new Func1<Object, Boolean>() {
//            @Override
//            public Boolean call(Object o) {
//                return eventType.isInstance(o);
//            }
//        }) .cast(eventType);
    }
}