不存在类型变量 T 的实例，因此 Flux<T> 确认为 Mono<?延长 R)

Question

我正在实施 Spring webflux 演示应用程序，并且已经编写了我的演示应用程序

package com.abcplusd.application;

import com.abcplusd.domain.Event;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Flux;

import java.util.Collections;
import java.util.Date;
import java.util.stream.Stream;

@SpringBootApplication
public class ReactiveClientApplication {

    @Bean WebClient webClient() {
        return WebClient.create("http://localhost:8080");
    }

    @Bean CommandLineRunner demo(WebClient webClient) {
        return args -> {
            webClient.get()
                .uri("/events")
                .accept(MediaType.TEXT_EVENT_STREAM)
                .exchange()
                .flatMap(clientResponse -> clientResponse.bodyToFlux(Event.class))
                .subscribe(System.out::println);
        };
    }
    public static void main(String[] args) {
        new SpringApplicationBuilder(ReactiveClientApplication.class)
            .properties(Collections.singletonMap("server.port", "8081"))
            .run(args);
    }
}

显示如下错误

Error:(29, 41) java: incompatible types: no instance(s) of type variable(s) T exist so that reactor.core.publisher.Flux<T> conforms to reactor.core.publisher.Mono<? extends R>

以上错误在这一行：

                    .flatMap(clientResponse -> clientResponse.bodyToFlux(Event.class)))

事件Class

import lombok.AllArgsConstructor;
import lombok.Data;

import java.util.Date;

@Data
@AllArgsConstructor
public class Event {
    private  long id;
    private Date when;
}

谁能帮我解决这个错误？

Answer 1

在我对代码进行这些更改后，它对我有效

.flatMap(clientResponse -> clientResponse.bodyToFlux(Event.class)))

到

.flatMapMany(clientResponse -> clientResponse.bodyToFlux(Event.class))

和

@NoArgsConstructor annotation in Event.Class

如下：

import java.util.Date;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Event {
    private  long id;
    private Date when;

}

Answer 2

flatMapMany 而不是 flatMap 有效。

然而，当您将属性 spring.main.web_environment=false 添加到 application.properties 文件时，webClient 根本不起作用。

不存在类型变量 T 的实例，因此 Flux<T> 确认为 Mono<?延长 R)

No instance(s) of type variable(s) T exist so that Flux<T> confirms to Mono<? extend R)

spring-boot

react-native-router-flux

spring-webflux

事件Class