RxJava的四种Subjects:PublishSubject、ReplaySubject、BehaviorSubject、AsyncSubject的理解
Subject:它既是Observable,又是observer。也就是既可以发送事件,也可以接收事件。
下面是四个子类PublishSubject、ReplaySubject、BehaviorSubject、AsyncSubject的区别:
PublishSubject<Integer> source = PublishSubject.create(); //PublicSubject:接收到订阅之后的所有数据。 // It will get 1, 2, 3, 4 and onComplete source.subscribe(getFirstObserver()); source.onNext(1); source.onNext(2); source.onNext(3); // It will get 4 and onComplete for second observer also. source.subscribe(getSecondObserver()); source.onNext(4); source.onComplete();
ReplaySubject<Integer> source = ReplaySubject.create(); //ReplaySubject:接收到所有的数据,包括订阅之前的所有数据和订阅之后的所有数据。 // It will get 1, 2, 3, 4 source.subscribe(getFirstObserver()); source.onNext(1); source.onNext(2); source.onNext(3); source.onNext(4); source.onComplete(); // It will also get 1, 2, 3, 4 as we have used replay Subject source.subscribe(getSecondObserver());
BehaviorSubject<Integer> source = BehaviorSubject.create(); //BehaviorSubject:接收到订阅前的最后一条数据和订阅后的所有数据。 // It will get 1, 2, 3, 4 and onComplete source.subscribe(getFirstObserver()); source.onNext(1); source.onNext(2); source.onNext(3); // It will get 3(last emitted)and 4(subsequent item) and onComplete source.subscribe(getSecondObserver()); source.onNext(4); source.onComplete();
AsyncSubject<Integer> source = AsyncSubject.create(); //AsyncSubject:不管在什么位置订阅,都只接接收到最后一条数据 // It will get only 4 and onComplete source.subscribe(getFirstObserver()); source.onNext(1); source.onNext(2); source.onNext(3); // It will also get only get 4 and onComplete source.subscribe(getSecondObserver()); source.onNext(4); source.onComplete();