Spring BOOT ( 基于Kotlin 编程语言) 使用 Spring WebFlux 实现响应式编程

最新推荐文章于 2024-11-26 22:43:42 发布

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最新推荐文章于 2024-11-26 22:43:42 发布

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本文介绍如何在Spring Boot中使用Spring WebFlux进行响应式编程，特别是基于Kotlin语言的实现方式。Spring WebFlux是Spring 5.0引入的全新响应式Web框架，不同于传统的Spring MVC，它不需要Servlet API支持，完全异步且非阻塞，并通过Reactor项目实现了Reactive Streams规范。文章展示了使用注解和函数式两种方式来定义路由。

Spring BOOT ( 基于Kotlin 编程语言) 使用 Spring WebFlux 实现响应式编程

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参考文档：https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#spring-webflux

The original web framework included in the Spring Framework, Spring Web MVC, was purpose built for the Servlet API and Servlet containers. The reactive stack, web framework, Spring WebFlux, was added later in version 5.0. It is fully non-blocking, supports
Reactive Streams
back pressure, and runs on servers such as Netty, Undertow, and Servlet 3.1+ containers.
Both web frameworks mirror the names of their source modules
spring-webmvcand
spring-webflux
and co-exist side by side in the Spring Framework. Each module is optional. Applications may use one or the other module, or in some cases both — e.g. Spring MVC controllers with the reactive
WebClient.

The Spring WebFlux Framework

Spring WebFlux is the new reactive web framework introduced in Spring Framework 5.0. Unlike Spring MVC, it does not require the Servlet API, is fully asynchronous and non-blocking, and implements the Reactive Streams specification through the Reactor project.

Spring WebFlux comes in two flavors: functional and annotation-based. The annotation-based one is quite close to the Spring MVC model we know, as shown in the following example:

@RestController
@RequestMapping("/users")
public class MyRestController {

    @GetMapping("/{user}")
    public Mono<User> getUser(@PathVariable Long user) {
        // ...
    }

    @GetMapping("/{user}/customers")
    Flux<Customer> getUserCustomers(@PathVariable Long user) {
        // ...
    }

    @DeleteMapping("/{user}")
    public Mono<User> deleteUser(@PathVariable Long user) {
        // ...
    }

}

‘WebFlux.fn’, the functional variant, separates the routing configuration from the actual handling of the requests, as shown in the following example:

@Configuration
public class RoutingConfiguration {

    @Bean
    public RouterFunction<ServerResponse> monoRouterFunction(UserHandler userHandler) {
        return route(GET("/{user}").and(accept(APPLICATION_JSON)), userHandler::getUser)
                .andRoute(GET("/{user}/customers").and(accept(APPLICATION_JSON)), userHandler::getUserCustomers)
                .andRoute(DELETE("/{user}").and(accept(APPLICATION_JSON)), userHandler::deleteUser);
    }

}

@Component
public class UserHandler {

    public Mono<ServerResponse> getUser(ServerRequest request) {
        // ...
    }

    public Mono<ServerResponse> getUserCustomers(ServerRequest request) {
        // ...
    }

    public Mono<ServerResponse> deleteUser(ServerRequest request) {
        // ...
    }
}

WebFlux is part of the Spring Framework. and detailed information is available in its reference documentation.

To get started, add the spring-boot-starter-webflux module to your application.

[Note]
Adding both spring-boot-starter-web and spring-boot-starter-webflux modules in your application results in Spring Boot auto-configuring Spring MVC, not WebFlux. This behavior has been chosen because many Spring developers add spring-boot-starter-webflux to their Spring MVC application to use the reactive WebCLient. You can still enforce your choice by setting the chosen application type to SpringApplication.setWebApplicationType(WebApplicationType.REACTIVE).

创建一个简单的 UserRepository 和 User DTO 类用来从列表中获取用户数据。这只是一个假的 Bean，在实际过程中你可以从包括关系数据库、MongoDB 或者是 RestClient 获取数据。