将RxJava observable的错误转换为另一个可观察和吞咽成功

Question

如何将observable的错误转换为另一个observable？

我正在尝试实现以下方案中显示的算法:

我正在使用一个名为Grokking RxJava的教程来开始我的学习,并发现flatMap运算符可以将一个Obtrable转换为Retrofit,另一个允许我对服务器方法进行一系列调用.但是在教程链接方法中总是返回成功结果.如果其中一个远程方法返回错误,我怎么能做同样的链接？

目前我正在使用一种看起来奇怪且不清楚的方法:

AppObservable.bindActivity(this, userService.checklogin(mPhone)
            .onErrorResumeNext(new Func1<Throwable, Observable<? extends Response>>() {
                @Override
                public Observable<? extends Response> call(Throwable throwable) {
                    return Observable.just(null);
                }
            }))
            .flatMap(new Func1<Response, Observable<Response>>() {
                @Override
                public Observable<Response> call(Response response) {
                    if (response == null) {
                        return AppObservable.bindActivity(RegistrationActivity.this, userService.register(
                                mPhone,
                                name.getText().toString(),
                                selectedSex,
                                selectedDateDay,
                                selectedDateMonth,
                                selectedDateYear,
                                Locale.getDefault().getLanguage(),
                                persistentUserInfoStore.getInstallationToken()
                        ));
                    }
                    phone.setError(getString(R.string.already_registered_phone));
                    progressDialog.dismiss();
                    return Observable.empty();
                }
            })
            .subscribe(new Action1<Response>() {
                @Override
                public void call(Response response) {
                    startConfirmationActivity();
                    progressDialog.dismiss();
                }
            }, new Action1<Throwable>() {
                @Override
                public void call(Throwable throwable) {
                    progressDialog.dismiss();
                    Toast.makeText(RegistrationActivity.this, "Error while register user", Toast.LENGTH_SHORT).show();
                }
            });

有没有更明确的方法来做到这一点.

PS我是RxJava的新手.

Answer 1

1. 你应该叫一个userService.register从onErrorResumeNext
2. 区分发生何种错误的最简单方法是Exception为每个错误引入一个单独的类.

这是它在代码中的样子:

userService.checkLogin(mPhone).flatMap(new Func1<Response, Observable<Response>() {
    @Override
    public Observable<? extends Response> call(final Response response) {
        // according to your diagram the whole Observable should fail if first call was successful
        return Observable.error(new FirstCallWasSuccessfulException(response));
    }
}).onErrorResumeNext(new Func1<Throwable, Observable<? extends Response>>() {
    @Override
    public Observable<? extends Response> call(final Throwable throwable) {
        if (throwable instanceof FirstCallWasSuccessfulException) {
            return Observable.error(throwable);
        }

        return userService.register(...);
    }
}).subscribe(new Subscriber<Response>() {
    @Override
    public void onError(final Throwable throwable) {
        if (throwable instanceof FirstCallWasSuccessfulException) {
            // foo
        } else {
            // bar
        }
    }

    @Override
    public void onNext(final Response response) {

    }

    @Override
    public void onCompleted() {

    }
});