我为演示应用程序进行了以下设置:
我有一个服务,该服务根据加密货币集合中存在的货币返回Flux
中的List<CryptoCurrencyRateDTO>
。我会为每种货币生成随机汇率,并将其流式传输到Web客户端。
服务是这样的:
@Service
public class CryptoCurrencyRateService {
@Autowired private CryptoCurrencyRateRepository rateRepository;
@Autowired private CryptoCurrencyRepository currencyRepository;
// constructor
public Flux<List<CryptoCurrencyRateDTO>> realtimeRates() {
return currencyRepository.findAll()
.map(CryptoCurrency::getSymbol)
.flatMap(rateRepository::findTopBySymbolOrderByTimestamp)
.zipWith(
Flux.<Long>generate(sink -> sink.next(Instant.now().toEpochMilli())),
(rate, timestamp) -> new CryptoCurrencyRate(rate.getSymbol(), timestamp, randomRateBasedOnPrevious )
)
.flatMap(rateRepository::save)
.map(rateMapper::toDto)
.collectList()
.delayElement(Duration.ofSeconds(5))
.repeat();
}
}
CryptoCurrencyRateRepository
如下:
@Repository
public interface CryptoCurrencyRateRepository extends ReactiveMongoRepository<CryptoCurrencyRate, String> {
Mono<CryptoCurrencyRate> findTopBySymbolOrderByTimestamp(String symbol);
}
但是,在调用.flatMap(rateRepository::findTopBySymbolOrderByTimestamp)
之后,我只得到一个包含1个项目的Flux
,而我想我会得到一个Flux
,其中包含{{1} }致电,因为我的加密货币集合包含3种货币。
当我查看日志记录时,发现对currencyRepository.findAll().map(CryptoCurrency::getSymbol)
的调用已执行了3次
findTopBySymbolOrderByTimestamp
答案 0 :(得分:1)
我无法重现您的问题。这就是我模仿的方式
public static void main(String[] args) {
Flux<String> stringFlux = Flux.fromStream(Stream.of("a", "b", "c"));
System.out.println(realtimeRates(stringFlux).blockFirst());
}
static Flux<List<String>> realtimeRates(Flux<String> list) {
Flux<String> symbols = list.map(Scratch::getSymbol);
Flux<String> topRates = symbols.flatMap(Scratch::findTopBySymbolOrderByTimestamp);
Flux<String> zip = topRates.zipWith(
Flux.<Long>generate(sink -> sink.next(Instant.now().toEpochMilli())),
(rate, timestamp) -> rate + timestamp.toString());
Mono<List<String>> listMono = zip.collectList();
Mono<List<String>> delayElement = listMono.delayElement(Duration.ofSeconds(5));
Flux<List<String>> repeat = delayElement.repeat();
return repeat;
}
static Mono<String> findTopBySymbolOrderByTimestamp(String symbol) {
return Mono.just("other-" + symbol);
}
static String getSymbol(String rate) {
return rate.toLowerCase();
}
如您所见,您将得到类似[other-a1542821666133, other-b1542821666133, other-c1542821666133]
的信息。
您如何检查平面图结果?请注意,如果您使用blockFirst()
或blockLast()
方法执行此操作,您将仅获得一个元素,因为其元素为Flux<String>
(请检查上面代码中的topRates
变量)< / p>
答案 1 :(得分:0)
看来我的期望是正确的。唯一出问题的是并非所有对象都丢失了,因为它们缺少ID。