如何在Android RxJava Observable中顺序运行2个查询? [英] How to run 2 queries sequentially in a Android RxJava Observable?
问题描述
我想运行2个异步任务,一个异步任务(依次).我已经读过有关ZIP或Flat的内容,但是我不太了解...
I want to run 2 asynchronous tasks, one followed by the other (sequentially). I have read something about ZIP or Flat, but I didn't understand it very well...
我的目的是从本地SQLite加载数据,完成后它将调用查询到服务器(远程).
My purpose is to load the data from a Local SQLite, and when it finishes, it calls the query to the server (remote).
有人可以建议我,实现这一目标的方法吗?
Can someone suggests me, a way to achieve that?
这是我正在使用的RxJava Observable框架(单个任务):
This is the RxJava Observable skeleton that I am using (single task):
// RxJava Observable
Observable.OnSubscribe<Object> onSubscribe = subscriber -> {
try {
// Do the query or long task...
subscriber.onNext(object);
subscriber.onCompleted();
} catch (Exception e) {
subscriber.onError(e);
}
};
// RxJava Observer
Subscriber<Object> subscriber = new Subscriber<Object>() {
@Override
public void onCompleted() {
// Handle the completion
}
@Override
public void onError(Throwable e) {
// Handle the error
}
@Override
public void onNext(Object result) {
// Handle the result
}
};
Observable.create(onSubscribe)
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(subscriber);
推荐答案
要执行此操作的操作员为merge
,请参见 http://reactivex.io/documentation/operators/merge.html .
The operator to do that would be merge
, see http://reactivex.io/documentation/operators/merge.html.
我的方法是创建两个可观察对象,例如observableLocal
和observableRemote
,然后合并输出:
My approach would be to create two observables, let's say observableLocal
and observableRemote
, and merge the output:
Observable<Object> observableLocal = Observable.create(...)
Observable<Object> observableRemote = Observable.create(...)
Observable.merge(observableLocal, observableRemote)
.subscribe(subscriber)
如果要确保在本地后运行远程,可以使用concat
.
If you want to make sure that remote is run after local, you can use concat
.
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