SpringBoot2使用WebFlux函数式编程的方法

2019-11-26 09:45:14

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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，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/> <!-- 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>

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 */@RestControllerpublic 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 */@Componentpublic 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 */@Configurationpublic class HiRouter {  @Bean  public RouterFunction<ServerResponse> routeCity(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：