[英]RxJava2: execute an async function for every item in a list and wait for callback
我正在努力与RxJava2。 我想对列表的每个项目执行一个函数。 这个功能:
public void function(final Result result) {
FirebaseFirestore.getInstance().collection(COLLECTION_NAME).document(result.getId()).get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
@Override
public void onSuccess(DocumentSnapshot documentSnapshot) {
// do some operation
}
});
}
此函数是异步并使用FirebaseFirestore。
所以我尝试在列表中使用RxJava2为每个项目调用函数:
Observable.fromIterable(resultList)
.concatMap(result -> Observable.fromCallable(new Callable<String>() {
@Override
public String call() throws Exception {
function(result);
return "ok";
}
}))
.subscribe(r -> {
// do some operation when all firebase async tasks are done
});
concatMap正常工作,并为列表中的每个项调用该函数。 问题是我需要在所有firebase异步任务完成后进行回调。
任何帮助将非常感激。
我将尝试绘制一个可能的解决方案:
public class Callback implements OnSuccessListener<DocumentSnapshot> {
private final ObservableEmitter<DocumentSnapshot> emitter;
private final boolean last;
public Callback(boolean lastvalue, ObservableEmitter<DocumentSnapshot> e) {
this.last = lastvalue;
this.emitter = e;
}
@Override
public void onSuccess(DocumentSnapshot value) {
emitter.onNext(value);
if (last) {
emitter.onComplete();
}
}
}
Observable<DocumentSnapshot> observable = Observable.create(new ObservableOnSubscribe<DocumentSnapshot>() {
@Override
public void subscribe(ObservableEmitter<DocumentSnapshot> e) throws Exception {
int i = 1;
for (Result result : resultList) {
/* callback object now knows which is the last request so it can emit the onComplete */
Callback callbackInstance = new Callback(resultList.size() == i, e);
i++;
FirebaseFirestore.getInstance().collection(COLLECTION_NAME)
.document(result.getId()).get().addOnSuccessListener(callbackInstance);
}
}
});
然后,当订户的onComplete
操作被命中时,应该完成对Firebase的所有请求。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.