RxJava 缓存中间结果

Question

我正在为 kaltura 视频平台开发 android 客户端，现在我正在开发上传视频。此功能包括以下步骤：

create MediaEntry

params: name, description

create UploadToken

params: fileName, mediaEntryId(which received at step 1)

addContent - in other words bind MediaEntry to UploadToken

params: mediaEntryId(which received at step 1), uploadTokenId(which received at step 2)

uploadVideo params: uploadTokenId(which received at step 2), videoData

这是我使用 RxJava 的代码：

API.createMediaEntry(name, description)
                    .flatMap(mediaEntry -> {
                        mediaEntryId = mediaEntry.getId();
                        return API.createUploadToken(this.videoUri.getPath(), mediaEntry.getId());
                    })
                    .flatMap(uploadToken -> {
                        uploadTokenId = uploadToken.getId();
                        return API.addContent(mediaEntryId, uploadToken.getId());
                    })
                    .flatMap(mediaEntry -> API.uploadVideo(uploadTokenId, FileUtil.getTypedVideoFileFromUri(this.videoUri, UploadVideoActivity.this)))
                    .doOnError(throwable -> {
                        throwable.printStackTrace();
                        dismissProgressDialog();
                    })
                    .doOnNext(response -> {

                    })
                    .doOnCompleted(() -> {
                        dismissProgressDialog();
                    })
                    .subscribe();

其中 API 是 Retrofit 支架适配器。

正如您从代码中看到的，我需要在 步骤 1 和 uploadTokenId[=] 中保存 mediaEntryId 32=] 在 步骤 2，在 步骤 3 使用它们。我想了解一下，有没有办法从 step 1 中保存 mediaEntry 和 [=] 中的 uploadToken 23=]步骤 2 稍后使用它们，或者可能有一些方法可以更改我的代码，以排除将数据保存到局部变量中？

对我来说理想的解决方案是这样的：

API.createMediaEntry(name, description) .doSomeThingWithMedaiEntry(mediaEntry -> mediaEntry) .flatMap(mediaEntry -> API.createUploadToken(this.videoUri.getPath(), mediaEntry.getId())) .doSomeThingWithUploadToken(token -> token) .getMediaEntryAndUploadTokenSomehow((mediaEntry, uploadToken) -> API.addContent(mediaEntry.getId(), uploadToken.getId())) .getUploadTokenSomehow(uploadToken -> API.uploadVideo(uploadToken.getId(), FileUtil.getTypedVideoFileFromUri(this.videoUri, UploadVideoActivity.this))) .doOnError(throwable -> { throwable.printStackTrace(); dismissProgressDialog(); }) .doOnNext(response -> { }) .doOnCompleted(() -> { dismissProgressDialog(); }) .subscribe();

Answer 1

除了使用元组之外，您还可以嵌套 Observables。

API.createMediaEntry(name, description)
    .flatMap(createdMediaEntry -> API.createUploadToken(this.videoUri.getPath(), createdMediaEntry.getId())
                    .flatMap(uploadToken -> API.addContent(createdMediaEntry.getId(), uploadToken.getId())
                                    .flatMap(addedMediaEntry -> API.uploadVideo(uploadToken.getId(), , , ))
                    )
    )
    ...

RxJava 缓存中间结果

RxJava cache intermediate results

reactive-programming

rx-java