SpringBoot2使用WebFlux函数式编程

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本文只是简单使用SpringBoot2使用WebFlux的函数式编程简单使用，后续会继续写关于Webflux相关的文章。

最近一直在研究WebFlux，后续会陆续出一些相关的文章。

首先看一下Srping官网上的一张图，对比一下SpringMvc和Spring WebFlux，如图：

在查看一下WebFlux的官方文档:https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#spring-webflux，WebFlux提供了函数式编程，本文简单介绍一下WebFlux函数式编程简单使用。

新建项目

创建一个项目，pom文件中引入webflux依赖，完整pom文件如下：

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.dalaoyang</groupId> <artifactId>springboot2_webflux</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>springboot2_webflux</name> <description>springboot2_webflux</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.3.RELEASE</version> <relativePath/>  </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-webflux</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>

首先试试引入WebFlux依赖之后，SpringMvc方式是否还能使用，新建一个HelloController，完整代码如下，执行后发现，是可以正常执行访问的，这其实就是我们所说的注解式编程。

package com.dalaoyang.controller;import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController;/** * @author dalaoyang * @project springboot_learn * @package com.dalaoyang.controller * @email yangyang@dalaoyang.cn * @date 2018/7/30 */ @RestController public class HelloController { @GetMapping("hello") public String Hello(){ return "Hello this is SpringWebFlux"; }}

结果如图：

接下来使用函数式编程，首先查阅一下官方文档，如图：

我们需要创建一个HandlerFunction返回值为Mono，新建一个HiHandler，里面写一个方法Hi，完整代码如下：

package com.dalaoyang.handler; import org.springframework.http.MediaType; import org.springframework.stereotype.Component; import org.springframework.web.reactive.function.BodyInserters; import org.springframework.web.reactive.function.server.ServerRequest; import org.springframework.web.reactive.function.server.ServerResponse; import reactor.core.publisher.Mono;/** * @author dalaoyang * @project springboot_learn * @package com.dalaoyang.handler * @email yangyang@dalaoyang.cn * @date 2018/7/30 */ @Component public class HiHandler { public Mono<ServerResponse> Hi(ServerRequest request) { return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON) .body(BodyInserters.fromObject("Hi , this is SpringWebFlux")); } }

其中ServerResponse是相应的封装对象，下面是它的源码，其中包含了响应状态，响应头等等，代码如下：

package org.springframework.web.reactive.function.server;import java.net.URI; import java.time.ZonedDateTime; import java.util.List; import java.util.Map; import java.util.Set; import java.util.function.BiFunction; import java.util.function.Consumer; import org.reactivestreams.Publisher; import org.springframework.core.ParameterizedTypeReference; import org.springframework.http.CacheControl; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpMethod; import org.springframework.http.HttpStatus; import org.springframework.http.MediaType; import org.springframework.http.ResponseCookie; import org.springframework.http.codec.HttpMessageWriter; import org.springframework.http.server.reactive.ServerHttpResponse; import org.springframework.util.MultiValueMap; import org.springframework.web.reactive.function.BodyInserter; import org.springframework.web.reactive.result.view.ViewResolver; import org.springframework.web.server.ServerWebExchange; import reactor.core.publisher.Mono;public interface ServerResponse { HttpStatus statusCode(); HttpHeaders headers(); MultiValueMap<String, ResponseCookie> cookies(); Mono<Void> writeTo(ServerWebExchange var1, ServerResponse.Context var2); static ServerResponse.BodyBuilder from(ServerResponse other) { return new DefaultServerResponseBuilder(other); } static ServerResponse.BodyBuilder status(HttpStatus status) { return new DefaultServerResponseBuilder(status); } static ServerResponse.BodyBuilder status(int status) { return new DefaultServerResponseBuilder(status); } static ServerResponse.BodyBuilder ok() { return status(HttpStatus.OK); } static ServerResponse.BodyBuilder created(URI location) { ServerResponse.BodyBuilder builder = status(HttpStatus.CREATED); return (ServerResponse.BodyBuilder)builder.location(location); } static ServerResponse.BodyBuilder accepted() { return status(HttpStatus.ACCEPTED); } static ServerResponse.HeadersBuilder<?> noContent() { return status(HttpStatus.NO_CONTENT); } static ServerResponse.BodyBuilder seeOther(URI location) { ServerResponse.BodyBuilder builder = status(HttpStatus.SEE_OTHER); return (ServerResponse.BodyBuilder)builder.location(location); } static ServerResponse.BodyBuilder temporaryRedirect(URI location) { ServerResponse.BodyBuilder builder = status(HttpStatus.TEMPORARY_REDIRECT); return (ServerResponse.BodyBuilder)builder.location(location); } static ServerResponse.BodyBuilder permanentRedirect(URI location) { ServerResponse.BodyBuilder builder = status(HttpStatus.PERMANENT_REDIRECT); return (ServerResponse.BodyBuilder)builder.location(location); } static ServerResponse.BodyBuilder badRequest() { return status(HttpStatus.BAD_REQUEST); } static ServerResponse.HeadersBuilder<?> notFound() { return status(HttpStatus.NOT_FOUND); } static ServerResponse.BodyBuilder unprocessableEntity() { return status(HttpStatus.UNPROCESSABLE_ENTITY); } public interface Context { List<HttpMessageWriter<?>> messageWriters(); List<ViewResolver> viewResolvers(); } public interface BodyBuilder extends ServerResponse.HeadersBuilder<ServerResponse.BodyBuilder> { ServerResponse.BodyBuilder contentLength(long var1); ServerResponse.BodyBuilder contentType(MediaType var1); ServerResponse.BodyBuilder hint(String var1, Object var2); <T, P extends Publisher<T>> Mono<ServerResponse> body(P var1, Class<T> var2); <T, P extends Publisher<T>> Mono<ServerResponse> body(P var1, ParameterizedTypeReference<T> var2); Mono<ServerResponse> syncBody(Object var1); Mono<ServerResponse> body(BodyInserter<?, ? super ServerHttpResponse> var1); Mono<ServerResponse> render(String var1, Object... var2); Mono<ServerResponse> render(String var1, Map<String, ?> var2); } public interface HeadersBuilder<B extends ServerResponse.HeadersBuilder<B>> { B header(String var1, String... var2); B headers(Consumer<HttpHeaders> var1); B cookie(ResponseCookie var1); B cookies(Consumer<MultiValueMap<String, ResponseCookie>> var1); B allow(HttpMethod... var1); B allow(Set<HttpMethod> var1); B eTag(String var1); B lastModified(ZonedDateTime var1); B location(URI var1); B cacheControl(CacheControl var1); B varyBy(String... var1); Mono<ServerResponse> build(); Mono<ServerResponse> build(Publisher<Void> var1); Mono<ServerResponse> build(BiFunction<ServerWebExchange, ServerResponse.Context, Mono<Void>> var1); } }

在回过头了看上面官方文档的图片，还需要配置一个路由来类似@RequestMapping的功能，通过RouterFunctions.route(RequestPredicate, HandlerFunction)提供了一个路由器函数默认实现，新建一个HiRouter，代码如下：

package com.dalaoyang.router;import com.dalaoyang.handler.HiHandler; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.http.MediaType; import org.springframework.web.reactive.function.server.RequestPredicates; import org.springframework.web.reactive.function.server.RouterFunction; import org.springframework.web.reactive.function.server.RouterFunctions; import org.springframework.web.reactive.function.server.ServerResponse; /** * @author dalaoyang * @project springboot_learn * @package com.dalaoyang.router * @email yangyang@dalaoyang.cn * @date 2018/7/30 */ @Configuration public class HiRouter { @Bean public RouterFunction<ServerResponse> routeHi(HiHandler hiHandler) { return RouterFunctions .route(RequestPredicates.GET("/hi") .and(RequestPredicates.accept(MediaType.APPLICATION_JSON)), hiHandler::Hi); } }