java - RxJava retryWhen 重试返回可完成的整个方法

Question

每次 API 以无效令牌错误（重新身份验证）响应时，我都会尝试重新验证令牌。我有这个小例子，它复制了我面临的问题。基本上，第一次调用会抛出一个异常，这会触发重试，当它重试时，auth 方法不会再次完全调用（它不会打印“Entered Auth”，而是打印“authing...”）。

public class Example {

AtomicInteger atom = new AtomicInteger(1);

public Example(){}

public void start(){
    auth().andThen(call())
            .retryWhen(throwableFlowable -> throwableFlowable.flatMap(throwable -> {
                System.out.println("Retrying...\n");
                return Flowable.timer(1, TimeUnit.SECONDS);
            }))
            .subscribe(integer -> System.out.println("Result: " + integer), e -> System.out.println("Error" + e.getMessage()));
}

public Completable auth(){
    System.out.println("Entered Auth");
    return Completable.create(emitter -> {
        System.out.println("authing...");
        emitter.onComplete();
    });
}

public Single<String> call(){
    return getId()
            .flatMap(this::getNameById);
}

public Single<Integer> getId(){
    return Single.create(emitter -> {
        emitter.onSuccess(atom.getAndIncrement());
    });
}

public Single<String> getNameById(int id){
    return Single.create(emitter -> {
        HashMap<Integer, String> hash = new HashMap<>();
        hash.put(1, "s");
        hash.put(2, "b");
        if(id == 1){
            emitter.onError(new Throwable());
        }else{
            emitter.onSuccess(hash.get(id));
        }
    });
}

}

同样，这是我的输出：

Entered Auth
authing...
Retrying...

authing...
Result: b

如何强制整个 auth() 方法在重试时运行？

Answer 1

使用Completable.defer，它将包装您的 Completable 创建并在重试时重做，而不仅仅是重新订阅。

 Completable.defer(() -> auth()).andThen(call())
                .retryWhen(throwableFlowable -> throwableFlowable.flatMap(throwable -> {
                    System.out.println("Retrying...\n");
                    return Flowable.timer(1, TimeUnit.SECONDS);
                }))
                .subscribe(integer -> System.out.println("Result: " + integer), e -> System.out.println("Error" + e.getMessage()));

输出：

Entered Auth
authing...
Retrying...

Entered Auth
authing...
Result: b