使用RxJava实现存储库模式

Question

I'm trying to figure out a better way to achieve something like repository pattern in RxJava in Android.

Here's what I have so far: (took some code from here )

public Subscription getData(Observer<Data> observer, boolean refresh) {
    Subscription sub = null;

    Data cached = getCachedData();
    if(cached != null) {
        observer.onNext(cached);
        if(refresh) {
            sub = requestNetwork().subscribe(observer);
        } else {
            observer.onCompleted();
        }
    } else {
        sub = requestNetwork().subscribe(observer);
    }

    return sub;
}

Basically it check if there's cached data stored, if not it'll make a network request. It also have refresh boolean parameter force it always make a network request.

The problem (or not) is, the caller of this function needs to call it will receive Subscription instead of Observable , which I can't chain anymore.

Is there a way to make the function return Observable but still have the repository pattern?

Answer 1

Thanks to akarnokd pointing me out to this article by Dan Lew.

My final code:

public Observable<Data> getData(boolean refresh) {
    Observable<Data> obs = Observable.concat(getCache(), requestNetwork());
    if(!refresh) {
        obs = obs.first(data -> data != null);
    }
    return obs;
}