java - PlayWS - 当请求超时时如何抛出异常？

Question

使用 PlayWS 执行长时间下载时，它使用 CompletableFuture ，这些有时会达到定义的请求超时。当发生这种情况时，PlayWS 似乎不会抛出异常(至少在我的配置中)，因此下载不能被标记为失败，并且尽管数据已损坏，但仍会进行处理。

请原谅这段令人厌恶的代码:

final CompletionStage<WSResponse> futureResponse = this.playWS.client
        .url(importSource.getDownloadUrl())
        .setMethod(HttpMethod.GET)
        .setRequestTimeout(Duration.ofSeconds(5)) // When the timeout is reached, the download gets canceled
        .stream();

try {
    futureResponse
            .thenAccept(res -> {
                try (OutputStream outputStream = Files.newOutputStream(file.toPath())) {
                    final Source<ByteString, ?> responseBody = res.getBodyAsSource();
                    final Sink<ByteString, CompletionStage<Done>> outputWriter =
                            Sink.foreach(bytes -> {
                                outputStream.write(bytes.toArray());
                            });
                    responseBody
                            .runWith(outputWriter, this.playWS.materializer)
                            .whenComplete((value, error) -> {
                                System.out.println("VALUE: "+value); // == "Done"
                                System.out.println("Error: "+error); // == null
                            })
                            .exceptionally(exception -> {
                                throw new IllegalStateException("Download failed for: " + importSource.getDownloadUrl(), exception);
                            })
                            .toCompletableFuture().join();
                } catch (final IOException e) {
                    throw new IllegalStateException("Couldn't open or write to OutputStream.", e);
                }
            })
            .exceptionally(exception -> {
                throw new IllegalStateException("Download failed for: " + importSource.getDownloadUrl(), exception);
            })
            .toCompletableFuture().get();
} catch (InterruptedException | ExecutionException e) {
    throw new IllegalStateException("Couldn't complete CompletableFuture.", e);
}

我是在做一些根本性错误的事情还是这是一个错误？

我看到的唯一解决方案是:

1. 计算接收到的字节数并将其与 Content-Length header 进行比较.
2. 将请求超时设置为 -1(无限期)。

感谢您的任何建议。

Answer 1

我认为有些过于复杂了。

您只需从 Future 或 CompletableStage 附加到 Source。 Akka Streams 拥有比 CompletableFuture 更强大的 API(我的观点)

final CompletionStage<WSResponse> futureResponse = this.playWS.client
        .url(importSource.getDownloadUrl())
        .setMethod(HttpMethod.GET)
        .setRequestTimeout(Duration.ofSeconds(5)) 
        .stream();

Source<WSResponse> source = Source.fromCompletableStage(futureResponse);
source.map(...).filter(...).recover(...).runforeach(..., playWS.materializer)