java RxJava + Retrofit - 进行多次调用
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RxJava + Retrofit - make multiple calls
提问by Arek Biela
I have a solid grasp of Retrofit when using sync and async calls. However, I encountered a small problem when creating some complex task, which I have to:
在使用同步和异步调用时，我对 Retrofit 有很好的掌握。但是，我在创建一些复杂的任务时遇到了一个小问题，我必须：
- Make a request in order to get List of ID's(about 20-30 ID's)
- After fetching ID's list, I would like to make async calls in order to get information about each object, defined by ID. I want to make 20-30 request in pararrel. I desire to observe it in order to update the UI after I manage to receive all the data from async calls.
- 发出请求以获取 ID 列表（大约 20-30 个 ID）
- 获取 ID 的列表后，我想进行异步调用以获取有关每个对象的信息，由 ID 定义。我想同时提出 20-30 个请求。我希望在我设法从异步调用接收所有数据后观察它以更新 UI。
I read about that issue and I realized that RxJava would solve my problem. But frankly, I have found it really hard so far to understand the whole process.
我读到了这个问题，我意识到 RxJava 可以解决我的问题。但坦率地说，到目前为止，我发现很难理解整个过程。
It would be great if I read some correct example in order to immerse into RxJava/RxAndroid issue.
如果我阅读一些正确的示例以便深入研究 RxJava/RxAndroid 问题，那就太好了。
回答by ffleandro
With this example you can get a list of ids, divide it in individual observables, call a service for each individual id and get notified ntimes for each getDetailsresponse.
通过这个例子，你可以获得一个 id 列表，将它划分为单独的 observables，为每个单独的 id 调用一个服务，并获得n每个getDetails响应的通知时间。
service.getIds()
.flatMap(ids -> Observable.from(ids))
.map(id -> service.getDetails(id))
.subscribe(detailed -> updateUi(detailed));
You can use the Observable.zipfunction to wait on several parallel calls, but I don't know if you can use it in a variable size call.
您可以使用该Observable.zip函数来等待多个并行调用，但我不知道您是否可以在可变大小的调用中使用它。
Take a look at this example:
看看这个例子：
Retrofit support for Observable also makes it easy to combine multiple REST calls together. For example, suppose we have one call that gets the photo and a second that gets the metadata. We can zip the results together:
对 Observable 的改造支持还使得将多个 REST 调用组合在一起变得容易。例如，假设我们有一个获取照片的调用和一个获取元数据的调用。我们可以将结果压缩在一起：
Observable.zip(
service.getUserPhoto(id),
service.getPhotoMetadata(id),
(photo, metadata) -> createPhotoWithData(photo, metadata))
.subscribe(photoWithData -> showPhoto(photoWithData));
回答by memoizr
It seems like what you're really looking for is info or examples on how to get started with RxJava, so I'd suggest you have a look at this excellent series of articles by Dan Lew: http://blog.danlew.net/2014/09/15/grokking-rxjava-part-1/
看起来您真正要寻找的是有关如何开始使用 RxJava 的信息或示例，因此我建议您查看 Dan Lew 撰写的这一系列出色的文章：http: //blog.danlew.net /2014/09/15/grokking-rxjava-part-1/
This series should contain enough material to give you a good idea of how to implement your feature.
本系列应该包含足够的材料，让您对如何实现您的功能有一个很好的了解。
