Question

我是RxJava编程的新手，需要帮助才能处理我的代码问题。我有以下代码：

public Single<List<Modifications>> loadModificationsImages() {
    return Observable.fromCallable(DataStoreRepository::loadModifications)
            .subscribeOn(Schedulers.io())
            .flatMapIterable(list -> list)
            .doOnNext(item -> {
                Observable.fromIterable(item.images)
                        .forEach(image -> {
                            ApiRepository.getModificationsImages(item.id, image.id)
                                    .subscribeOn(Schedulers.computation())
                                    .retry(3)
                                    .subscribe(response -> {
                                        InputStream is = response.byteStream();

                                        BitmapFactory.Options options = new BitmapFactory.Options();
                                        options.inPreferredConfig = Bitmap.Config.RGB_565;

                                        Bitmap bitmap = BitmapFactory.decodeStream(is, null, options);

                                        String contentSubType = response.contentType().subtype();
                                        String fileName = "modifications_id_" + item.id + "_image_id_" + image.id + "." + contentSubType;
                                        FileUtil.saveBitmap(bitmap, fileName);

                                        Modifications.Images img = new Modifications.Images(image.id, fileName, image.type);
                                        DataStoreRepository.updateModificationsImage(img, item.id);
                                    });
                        });
            })
            .toList();
}

它完美无缺，但我需要将每个Modifications.Images收集到一个集合中，并将其传递给方法（DataStoreRepository.updateListOfModificationsImage(List<Modifications.Images> images, int id)）以更新数据库。所以，这一行的问题是：

Modifications.Images img = new Modifications.Images(image.id, fileName, image.type);
DataStoreRepository.updateModificationsImage(img, item.id);

它只是使用单个项目覆盖数据库中的记录。我试图通过应用Collection修改给定的代码，但它对我不起作用。

感谢您的帮助！

Answer 1

在回调中订阅几乎总是错误的。否则，您应该toList图像，然后调用批量更新方法：

public Single<List<Modifications>> loadModificationsImages() {
    return Observable.fromCallable(DataStoreRepository::loadModifications)
            .subscribeOn(Schedulers.io())
            .flatMapIterable(list -> list)
            .flatMapSingle(item -> 
                Observable.fromIterable(item.images)
                .flatMap(image ->
                    ApiRepository.getModificationsImages(item.id, image.id)
                    .subscribeOn(Schedulers.io())
                    .retry(3)
                    .map(response -> {
                        InputStream is = response.byteStream();

                        BitmapFactory.Options options = new BitmapFactory.Options();
                        options.inPreferredConfig = Bitmap.Config.RGB_565;

                        Bitmap bitmap = BitmapFactory.decodeStream(is, null, options);

                        String contentSubType = response.contentType().subtype();
                        String fileName = "modifications_id_" + item.id + "_image_id_"
                            + image.id + "." + contentSubType;
                        FileUtil.saveBitmap(bitmap, fileName);

                        Modifications.Images img = new Modifications.Images(
                            image.id, fileName, image.type);
                        return img;
                    })
                )
                .toList()
                .doOnSuccess(images -> 
                    DataStoreRepository.updateListOfModificationsImage(images, image.id)
                )
            );
}

RxJava2：需要帮助来修复代码中的问题

1 个答案: