https://grokonez.com/spring-framework/spring-webflux/springboot-webflux-functional-restapis

SpringBoot WebFlux Functional RestAPIs

Reactive programming is about non-blocking applications. And Spring Framework 5 includes a new spring-webflux module, supports Reactive Streams for communicating backpressure across async components and libraries. So in the tutorial, JavaSampleApproach will guide you through the steps for creating a SpringBoot WebFlux Functional restful APIs.

Related posts:

• SpringBoot WebFlux Annotation-based RestAPIs – Reactor – Simple Ways to create Flux/Mono
• Spring WebClient with Spring Webflux | SpringBoot 2

I. Technologies

– Java: 1.8
– Maven: 3.3.9
– Spring Tool Suite: Version 3.9.0.RELEASE
– Spring Boot: 2.0.0.M4
– Spring Boot Starter Webflux

II. Spring WebFlux Functional

Spring Framework 5.0 supports WebFlux with fully asynchronous and non-blocking and does NOT require the Servlet API(Unlike Spring MVC).

Spring WebFlux supports 2 distinct programming models:
– Annotation-based with @Controller
– Functional with Java 8 lambda style

In the tutorial, we will introduce WebFlux with Functional.
For starting with WebFlux, SpringBoot supports a collection dependency: spring-boot-starter-webflux.

With Spring WebFlux Functional, we use {HandlerFunctions, RouterFunctions} to develop.

1. HandlerFunctions

HandlerFunctions will handle incoming HTTP requests through ServerRequest, and return a Mono

@Component
public class CustomerHandler {
    
    ...
    
    public Mono getAll(ServerRequest request) {
        ...
        return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(customers, Customer.class);
    }
    
    ...
    
    public Mono putCustomer(ServerRequest request) {
        ...
        return responseMono
                .flatMap(cust -> ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(fromObject(cust)));
    }

    ...
    
    public Mono deleteCustomer(ServerRequest request) {
        ...
        return responseMono
                .flatMap(strMono -> ServerResponse.ok().contentType(MediaType.TEXT_PLAIN).body(fromObject(strMono)));
    }
}

2. RouterFunction

RouterFunction handle all incoming requests. It takes a ServerRequest, and returns a Mono. If a request matches a particular route, a handler function is returned; otherwise it returns an empty Mono.

More at:

https://grokonez.com/spring-framework/spring-webflux/springboot-webflux-functional-restapis

SpringBoot WebFlux Functional RestAPIs