Question

这是我想要实现的目标：

查询数据库并发出项目。这在db thread上运行。
在步骤1之后，调用api刷新并将新结果保存到db中，然后发出新结果。这在网络线程上运行。

所以我的问题是，如何将两者合并为一个Observable并让订阅者更新每个onNext（）中的ui？这是我当前的代码，感觉有点反模式：

public Observable<List<Expense>> call() {
                    return Observable.create(new Observable.OnSubscribe<List<Expense>>() {
                        @Override
                        public void call(final Subscriber<? super List<Expense>> subscriber) {
                            List<Expense> expenses = fromLocal();
                            subscriber.onNext(expenses);
                            GetExpensesJob getExpensesJob = job.get();
                            getExpensesJob.setPage(page).setCount(count);
                            if (expenses == null || expenses.size() == 0 || getExpensesJob.shouldRun()) {
                                getExpensesJob.run().doOnNext(new Action1<List<Expense>>() {
                                    @Override
                                    public void call(List<Expense> expenses) {

                                        if (expenses != null) {

                                            .... save in db...
                                            subscriber.onNext(expenses);                                            
                                        }
                                    }
                                }).doOnError(new Action1<Throwable>() {
                                    @Override
                                    public void call(Throwable throwable) {
                                        subscriber.onError(throwable);
                                    }
                                }).subscribeOn(ApiModule.scheduler()).subscribe();

                            }
                        }
                    }).subscribeOn(Schedulers.io())

                            .observeOn(AndroidSchedulers.mainThread());

                }
            },
            new Action2<ExpensesView, List<Expense>>() {
                @Override
                public void call(ExpensesView expensesView, List<Expense> response) {
                    expensesView.stopLoading();
                    expensesView.onData(response);
                }
            },
            new Action2<ExpensesView, Throwable>() {
                @Override
                public void call(ExpensesView expensesView, Throwable throwable) {
                    expensesView.showError(throwable);
                }

Answer 1

（代表OP发布）

我还没有收到任何答案，但我想出了如何做到这一点。如果这对您有帮助，代码将如下：

Observervable dbObs = Observabe.create(...).subscribeOn(...);     
Observable  apiObs = Observable.create(...).subscribeOn(...);    
Observable.concat(dbObs,apiObs).subscribe(...)

这里的诀窍是你需要从你的observable调用subscriber.onComplete，否则后续的Observable不会获得订阅。

组合在不同线程中运行的两个Observable

1 个答案: