本文只是簡單使用SpringBoot2使用WebFlux的函數式編程簡單使用，后續會繼續寫關于Webflux相關的文章。

最近一直在研究WebFlux，后續會陸續出一些相關的文章。

首先看一下Srping官網上的一張圖，對比一下SpringMvc和Spring WebFlux，如圖：

在查看一下WebFlux的官方文檔:docs.spring.io/spring/docs…，WebFlux提供了函數式編程，本文簡單介紹一下WebFlux函數式編程簡單使用。

新建項目

創建一個項目，pom文件中引入webflux依賴，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/> <!-- lookup parent from repository --></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> 復制代碼

首先試試引入WebFlux依賴之后，SpringMvc方式是否還能使用，新建一個HelloController，完整代碼如下，執行后發現，是可以正常執行訪問的，這其實就是我們所說的注解式編程。

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";}} 復制代碼

結果如圖：

接下來使用函數式編程，首先查閱一下官方文檔，如圖：

我們需要創建一個HandlerFunction返回值為Mono，新建一個HiHandler，里面寫一個方法Hi，完整代碼如下：

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"));} } 復制代碼

其中ServerResponse是相應的封裝對象，下面是它的源碼，其中包含了響應狀態，響應頭等等，代碼如下：

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);} } 復制代碼

在回過頭了看上面官方文檔的圖片，還需要配置一個路由來類似@RequestMapping的功能，通過RouterFunctions.route(RequestPredicate, HandlerFunction)提供了一個路由器函數默認實現，新建一個HiRouter，代碼如下：

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 {@Beanpublic RouterFunction<ServerResponse> routeHi(HiHandler hiHandler) {return RouterFunctions.route(RequestPredicates.GET("/hi").and(RequestPredicates.accept(MediaType.APPLICATION_JSON)),hiHandler::Hi);} } 復制代碼

啟動項目，通過控制臺可以看到，兩種方式的映射都被打印出來了，如圖所示：

在瀏覽器訪問，http://localhost:8080/hi,結果如圖所示:

源碼下載 ：大老楊碼云

個人網站：www.dalaoyang.cn

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