java Zip 2在Spring Webfux中的不同Mono

Question

我有下面的功能

public Mono<CarAndShip> getCarAndShip(Long id) {
    Mono<Car> carMono = carService.getCar(id).subscribeOn(Schedulers.elastic());
    Mono<Ship> shipMono = shipService.getShip(id).subscribeOn(Schedulers.elastic());

    return Mono.zip(carMono, shipMono)
        .flatMap(zipMono -> {
            return new CarAndShip(zipMono.getT1(), zipMono.getT2());
        });

IntelliJ在返回声明中抱怨：

Required type: Mono <CarAndShip> 
Provided: Mono <Object> no
instance(s) of type variable(s) R exist so that CarAndShip conforms to Mono<? extends R>

如何将cast类型转换为所需的CarAndShip返回类型

Answer 1

Required type: Mono Provided: Mono no instance(s) of type variable(s) R exist so that CarAndShip conforms to Mono<? extends R>

例外情况是：你没有提供单声道

所以要么使用map而不是flatMap：

return Mono.zip(carMono, shipMono)
    .map(zipMono -> new CarAndShip(zipMono.getT1(), zipMono.getT2()));

或者提供单声道（这里可能不是最好的方式）：

return Mono.zip(carMono, shipMono)
    .flatMap(zipMono -> Mono.just(new CarAndShip(zipMono.getT1(), zipMono.getT2())));

Answer 2

在本例中，您应该使用map()而不是flatMap()，因为您没有返回Mono