如何将RX.Observable转换为IO.reactivex.Observable

import io.reactivex.Observable;
import io.reactivex.schedulers.Schedulers;
import rx.Observable.Transformer;
import rx.schedulers.Schedulers;

Transformer<T, T> rxToIoTransformer = new Transformer<T, T>() {
    @Override
    public Observable<T> call(Observable<T> observable) {
        return observable.subscribeOn(Schedulers.io())
                .observeOn(Schedulers.io());
    }
};

RX.Observable<T> rxObservable = ...; // 原始的RX.Observable
IO.reactivex.Observable<T> ioObservable = rxObservable.compose(rxToIoTransformer);