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我想使用 rxjava Observable 在 Retrofit 中处理分页。我听从了另一个问题的建议。

我有 100 多个页面需要获取，但链在第 20 页左右失败，并停止对可观察对象的任何进一步订阅，并在 logcat 中使用以下日志

04-04 04:12:11.766    2951-3012/com.example.app I/dalvikvm﹕ threadid=28: stack overflow on call to Ljava/util/concurrent/atomic/AtomicLongFieldUpdater$CASUpdater;.compareAndSet:ZLJJ
04-04 04:12:11.766    2951-3012/com.example.app I/dalvikvm﹕ method requires 56+20+32=108 bytes, fp is 0x94b52350 (80 left)
04-04 04:12:11.766    2951-3012/com.example.app I/dalvikvm﹕ expanding stack end (0x94b52300 to 0x94b52000)
04-04 04:12:11.766    2951-3012/com.example.app I/dalvikvm﹕ Shrank stack (to 0x94b52300, curFrame is 0x94b548dc)

有谁知道为什么会发生这种情况？

更新：我知道这是由于递归而发生的，但是有没有更优雅的方式来处理使用改造和 rxjava 的分页？

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1 回答 1

29

所以，鉴于我回答了你提到的原始问题，我可能也应该尝试回答这个案例。:)

这是我最初的分页答案的另一个有效（并且可能更简单）的替代方案，现在我已经在我的武器库中开发了更多的 Rx 技巧。:) （在 java8 lambda 风格的伪代码中完成）：

Observable.range(Integer.MAX_VALUE)
    // Get each page in order.
    .concatMap(page -> getResults(page))
    // Take every result up to and including the one where the next page index is null.
    .takeUntil(result -> result.next == null)
    // Add each output to a list builder. I'm using Guava's ImmutableList, but you could
    // just as easily use a regular ArrayList and avoid having to map afterwards. I just
    // personally prefer outputting an immutable data structure, and using the builder
    // is natural for this.
    //
    // Also, if you wanted to have the observable stream the full output at each page,
    // you could use collect instead of reduce. Note it has a slightly different syntax. 
    .reduce(
        ImmutableList.<ResponseObject>builder(),
        (builder, response) -> builder.addAll(response.results))
    // Convert list builder to one List<ResponseObject> of all the things.
    .map(builder -> builder.build())
    .subscribe(results -> { /* Do something with results. */ });
于 2015-04-12T20:19:32.440 回答