【pom.xml】

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
    <version>2.3.12.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
    <version>2.3.12.RELEASE</version>
</dependency>

【application.properties】

server.port=8081

【MyWebFluxTest.java】

package com.chz.myWebFlux;

@SpringBootApplication
public class MyWebFluxTest {

    public static void main(String[] args) {
        SpringApplication.run(MyWebFluxTest.class, args);
    }
}

【HelloWebFluxController.java】

package com.chz.myWebFlux.controller;

@RestController
public class HelloWebFluxController {

    @GetMapping("/hello")
    public String hello() {
        return "Hello, WebFlux !";
    }

    @GetMapping("/hello2")
    public Mono<String> hello2() {
        return Mono.just("Hello, WebFlux 2!");
    }

    @GetMapping("/user")
    public Mono<User> getUser() {
        User user = new User();
        user.setName("chz");
        user.setDesc("chz_desc");
        return Mono.just(user);
    }
}

【User.java】

package com.chz.myWebFlux.entity;

@Getter
@Setter
public class User {
    private String name;
    private String desc;
}

启动【MyWebFluxTest】

访问【http://localhost:8081/hello】，正常显示

访问【http://localhost:8081/hello2】，正常显示

访问【http://localhost:8081/user】，正常显示