RxJavaでファイルダウンロード

Download.java

public class Download {

    public Observable<File> download(List<String> target) {
        return Observable.from(target)
                .map(new Func1<String, okhttp3.Request>() {
                    @Override
                    public okhttp3.Request call(String url) {
                        return new Request.Builder().url(url).build();
                    }
                })
                .map(new Func1<Request, File>() {
                    @Override
                    public File call(Request request) {
                        try {
                            okhttp3.Response response =
                                    new OkHttpClient.Builder().build().newCall(request).execute();
                            if (!response.isSuccessful()) throw new IOException("");

                            Bitmap bitmap = BitmapFactory.decodeStream(response.body().byteStream());
                            // TODO: bitmap into file
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                        return null;
                    }
                });
    }
}