如何在 Retrofit2/rxJava 中刷新 ACCESS-TOKEN

Question

我提出一个请求（任何、授权、注册等），然后我才发现我需要更新ACCESS-TOKEN，即我收到错误401。

这是授权请求：

BaseApplication.getApiClient()
            .signIn(accessToken, body)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new SingleObserver<UserProfile>() {
                @Override
                public void onSubscribe(Disposable d) {
                    Log.d("-- SignInOnSubscribe", "Subscribed!");
                }

                @Override
                public void onSuccess(UserProfile userProfile) {
                    if (userProfile.getErrorDetails() != null) {
                        onSignInFinishedCallback.onLoginFailure(userProfile.getErrorDetails());
                        Log.d("-- SignInOnError", userProfile.getErrorDetails());
                    } else {
                        onSignInFinishedCallback.onLoginSuccess(userProfile);
                        profileRepository.updateUserProfile(userProfile);

                        Log.d("-- SignInOnSuccess", userProfile.getName());
                    }
                }

                @Override
                public void onError(Throwable e) {
                    Log.d("-- SignInOnError", e.getMessage());

                    if (e.getMessage().equals(Constants.CODE_UNAUTHORIZED)){
                        // Action on error 401
                    }

                    onSignInFinishedCallback.onLoginFailure(e.getMessage());
                }
            });

API 请求：

@POST("/api/login")
Single<UserProfile> getAccessToken(@Body Map<String, String> requestBody);

@POST("/api/abonent/login")
Single<UserProfile> signIn(@Header("X-ACCESS-TOKEN") String accessToken,
                             @Body Map<String, String> requestBody);

例如授权请求为request 1，接收TOKEN的请求为query 2。

问题：如果我在query 1 中收到错误，并且在query 2 成功后，我如何更新TOKEN，然后再执行query 1？

Answer 1

我不确定您是如何收到新令牌的，因为getAccessToken() 的返回类型是Single<UserProfile>。我想应该是Single<String>。也许情况并非如此，您会在标头或UserProfile 的字段中收到令牌。无论哪种情况，您都可以从以下解决方案中获得一个想法并根据您的情况进行调整。

方法是，我们从您的原始 observable 创建一个新的 observable，该 observable 使用令牌存储，其中包含最新的令牌。我们使用 compose 和 onErrorResumeNext 处理 401 错误，以便发出令牌刷新请求，将新令牌保存到令牌存储区，并使用新令牌重试原始请求。

更详细的解释见下面代码中的cmets：

public void signIn(final Map<String, String> body) {
    Single
            // Wrap the original request with a "defer" so that the access token is
            // evaluated each time it is called. This is important because the refreshed
            // access token should be used the second time around.
            .defer(new Callable<SingleSource<UserProfile>>() {
                @Override
                public SingleSource<UserProfile> call() throws Exception {
                    return BaseApplication.getApiClient()
                            .signIn(accessTokenStore.getAccessToken(), body);
                }
            })
            // Compose it with a transformer that refreshes the token in the token store and
            // retries the original request, this time with the refreshed token.
            .compose(retryOnNotAuthorized(body))

            // The code remains the same from here.
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new SingleObserver<UserProfile>() {
                @Override
                public void onSubscribe(Disposable d) {
                    Log.d("-- SignInOnSubscribe", "Subscribed!");
                }

                @Override
                public void onSuccess(UserProfile userProfile) {
                    if (userProfile.getErrorDetails() != null) {
                        onSignInFinishedCallback.onLoginFailure(userProfile.getErrorDetails());
                        Log.d("-- SignInOnError", userProfile.getErrorDetails());
                    } else {
                        onSignInFinishedCallback.onLoginSuccess(userProfile);
                        profileRepository.updateUserProfile(userProfile);

                        Log.d("-- SignInOnSuccess", userProfile.getName());
                    }
                }

                @Override
                public void onError(Throwable e) {
                    Log.d("-- SignInOnError", e.getMessage());

                    if (e.getMessage().equals(Constants.CODE_UNAUTHORIZED)) {
                        // Action on error 401
                    }

                    onSignInFinishedCallback.onLoginFailure(e.getMessage());
                }
            });
}

@NonNull
private SingleTransformer<UserProfile, UserProfile> retryOnNotAuthorized(final Map<String, String> body) {
    return new SingleTransformer<UserProfile, UserProfile>() {
        @Override
        public SingleSource<UserProfile> apply(final Single<UserProfile> upstream) {
            // We use onErrorResumeNext to continue our Single stream with the token refresh
            // and the retrial of the request.
            return upstream.onErrorResumeNext(new Function<Throwable, SingleSource<? extends UserProfile>>() {
                @Override
                public SingleSource<UserProfile> apply(Throwable throwable) throws Exception {
                    if (throwable instanceof HttpException
                            && ((HttpException) throwable).code() == 401) {
                        return BaseApplication.getApiClient().getAccessToken(body)
                                // I always use doOnSuccess() for non-Rx side effects, such as caching the token.
                                // I think it's clearer than doing the caching in a map() or flatMap().
                                .doOnSuccess(new Consumer<String>() {
                                    @Override
                                    public void accept(String accessToken) throws Exception {
                                        // Save the access token to the store for later use.
                                        accessTokenStore.storeAccessToken(accessToken);
                                    }
                                })
                                // We don't need the result of getAccessToken() any more, so I
                                // think it's cleaner to convert the stream to a Completable.
                                .toCompletable()

                                // After the token is refreshed and stored, the original request
                                // should be repeated.
                                .andThen(upstream);
                    }

                    // If the error was not 401, pass through the original error
                    return Single.error(throwable);
                }
            });
        }
    };
}

更新： 令牌存储只是一个带有 get 和 store 方法的常规接口。您应该将其实现为 POJO（将令牌存储在字段中），或者您可以将令牌存储在共享首选项中，以便令牌在应用重新启动后仍然存在。