Question

我得到一个Publisher<DataBuffer> inputStream作为参数。我想将该流转换为字符串，记录该字符串，然后必须将该字符串作为Publisher再次传递给另一种方法。

示例：

public Flux<Object> decode(Publisher<DataBuffer> inputStream) {
    return DataBufferUtils.join(inputStream)
                .map(buffer -> StandardCharsets.UTF_8.decode(buffer.asByteBuffer()).toString())
                .doOnNext(arg -> LOGGER.info(arg))
                .map(arg -> library.delegate(Mono.fromSupplier(() -> arg))) 
                .flatMapIterable(arg -> {
                     System.out.println(arg); //instanceof FluxLift??
                     return List.of(arg);
                );
}

class ExternalLibrary {
    //this ALWAYS returns a FluxLift
    public Flux<Object> delegate(Publisher<String> inputString) {
        //does not matter, I don't have control of this.
        //lets assume it does the following:

        return Flux.just(input).
            flatMapIterable(buffer -> List.of("some", "result"))
            .map(arg -> arg);
    }
}

问题：为什么最后一个flatMapInterable()中的参数总是为FluxLift类型？而且：如何在这里返回实际值？

Answer 1

为什么最终的flatMapInterable（）中的参数始终为FluxLift类型？

因为您的地图函数返回Flux

.map(arg -> library.delegate(Mono.fromSupplier(() -> arg)))

如何在这里返回实际值？

当映射函数返回反应类型时，请使用flatMap*函数之一而不是map。 flatMapMany适合您的情况：

public Flux<Object> decode(Publisher<DataBuffer> inputStream) {
    return DataBufferUtils.join(inputStream) //Mono<DataBuffer>
                .map(buffer -> StandardCharsets.UTF_8.decode(buffer.asByteBuffer()).toString()) //Mono<String>
                .doOnNext(arg -> LOGGER.info(arg)) //Mono<String>
                .flatMapMany(arg -> library.delegate(Mono.fromSupplier(() -> arg))) // Flux<Object>
                .flatMapIterable(arg -> {
                     System.out.println(arg); // instanceof Object
                     return List.of(arg);
                );

如何在通量流中而不是FluxLift中获得实际值？

1 个答案: