SpringBoot2使用WebFlux函数式编程

待我称王封你为后i 2022-05-18 06:45 187阅读 0赞

> 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：

![1][]

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][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：

![2][]

接下来使用函数式编程，首先查阅一下官方文档，如图：

![3][]

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);
        }
    }

启动项目，通过控制台可以看到，两种方式的映射都被打印出来了，如图所示：

![4][]

在浏览器访问，[http://localhost:8080/hi][http_localhost_8080_hi],结果如图所示:

![5][]

源码下载 ：[大老杨码云][Link 1]

个人网站：[https://www.dalaoyang.cn][https_www.dalaoyang.cn]

[1]: /images/20220518/dfa866b206a0450a86dfb6978a85ba87.png
[https_docs.spring.io_spring_docs_current_spring-framework-reference_web-reactive.html_spring-webflux]: https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#spring-webflux
[2]: /images/20220518/895894465c9c41e7a0241c99611f3a4a.png
[3]: /images/20220518/702407a3ac52475fb23c01e6dd2467c5.png
[4]: /images/20220518/57dfc74f8c17486f91ea029217c2b41b.png
[http_localhost_8080_hi]: http://localhost:8080/hi
[5]: /images/20220518/17f1c66f5a11493d86338a5d50984c82.png
[Link 1]: https://gitee.com/dalaoyang/springboot_learn
[https_www.dalaoyang.cn]: https://www.dalaoyang.cn