使用 Rx java Observable 一次进行多个异步调用（fire and forget calls）

Question

我有一个下游 api 调用列表（大约 10 个），我需要立即异步调用它们。到目前为止，我一直在使用可调用文件

List<RequestContextPreservingCallable <FutureResponse>> callables

我会将 api 调用添加到此列表，并在末尾使用 executeAsyncNoReturnRequestContextPreservingCallables 提交它。

使用 Rx java Observables 我该怎么做？

List<RequestContextPreservingCallable<FutureResponse>> callables = new 
ArrayList<RequestContextPreservingCallable<FutureResponse>>();

callables.add(apiOneConnector.CallToApiOne(name));
callables.add(apiTwoConnector.CallToApiTWO(sessionId));
....

//execute all the calls
executeAsyncNoReturnRequestContextPreservingCallables(callables);

Answer 1

您可以使用 zip 运算符。 zip operator 可以获取多个 observables 并同时执行它们，并在所有结果到达后继续执行。

然后您可以将这些结果转换为您需要的形式并传递到下一个级别。

按照你的例子。假设您有多个 API 调用来获取名称和会话等，如下所示

Observable.zip(getNameRequest(), getSessionIdRequest(), new BiFunction<String, String, Object>() {
        @Override
        public Object apply(String name, String sessionId) throws Exception {
            // here you will get all the results once everything is completed. you can then take these 
            // results and transform into another object and returnm from here. I decided to transform the results into an Object[]
            // the retuen type of this apply funtion is generic, so you can choose what to return
            return new Object[]{name, sessionId};
        }
    })
    .subscribeOn(Schedulers.io())  // will start this entire chain in an IO thread
    .observeOn(AndroidSchedulers.mainThread()) // observeOn will filp the thread to the given one , so that the downstream will be executed in the specified thread. here I'm switching to main at this point onwards
    .subscribeWith(new DisposableObserver<Object>() {
        @Override
        public void onNext(Object finalResult) {
           // here you will get the final result with all the api results
        }

        @Override
        public void onError(Throwable e) {
            // any error during the entire process will be triggered here
        }

        @Override
        public void onComplete() {
             //will be called once the whole chain is completed and terminated
        }
    });

您甚至可以将可观察值列表传递给 zip，如下所示

    List<Observable<String>> requests = new ArrayList<>();
    requests.add(getNameRequest());
    requests.add(getSessionIdRequest());

    Observable.zip(requests, new Function<Object[], Object[]>() {
        @Override
        public Object[] apply(Object[] objects) throws Exception {
            return new Object[]{objects[0], objects[1]};
        }
    }).subscribeWith(new DisposableObserver<Object[]>() {
        @Override
        public void onNext(Object[] objects) {

        }

        @Override
        public void onError(Throwable e) {

        }

        @Override
        public void onComplete() {

        }
    })

使用 Rx java Observable 一次进行多个异步调用（fire and forget calls）

Make multiple asynchronous calls(fire and forget calls) at once using Rx java Observable

java

spring-boot

rx-java

observable

callable