使用 Spring Boot WebFlux 构建Rest服务实验手册(一)

Spring WebFlux 是 Spring 5.0 推出的新的Web框架，主要是使用新的非阻塞（NIO）编程模型提高在某些场景下Web服务性能。本实验手册给学员演示如何使用该框架。

构建项目

构建一个新的 maven 项目，

groupId: cn.com.hohistar.spbt
artifactId: webflux-starter

然后将 pom.xml 文件修改为以下内容:

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.2.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>cn.com.hohistar.spbt</groupId>
	<artifactId>webflux-starter</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>webflux-starter</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot.experimental</groupId>
			<artifactId>spring-boot-starter-data-r2dbc</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-webflux</artifactId>
		</dependency>

		<dependency>
			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>io.r2dbc</groupId>
			<artifactId>r2dbc-h2</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<optional>true</optional>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot.experimental</groupId>
			<artifactId>spring-boot-test-autoconfigure-r2dbc</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>io.projectreactor</groupId>
			<artifactId>reactor-test</artifactId>
			<scope>test</scope>
		</dependency>
	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.boot.experimental</groupId>
				<artifactId>spring-boot-bom-r2dbc</artifactId>
				<version>0.1.0.M3</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
		</repository>
	</repositories>
</project>

新建Model类

新建名为: cn.com.hohistar.spbt.webfluxstarter.model 的包，然后在包中新建一个名为 Todo 的类, 内容为:

@Data
@AllArgsConstructor
public class Todo {

    private Integer id;

    private String title;

    private String desc;
}

新建Api接口

新建名为: cn.com.hohistar.spbt.webfluxstarter.api 的包，然后在包中新建名为: TodoApi 的类, 内容为:

@RestController
public class TodoFluxApi {


    @GetMapping("/api/todo")
    public Flux<Todo> getAllTodos() {

        Flux<Todo> res = Flux.fromArray(new Todo[] { new Todo(1, "todo1", "desc1"), new Todo(2, "todo2", "desc2")});
        return res;
    }
}

新建启动类

在包： cn.com.hohistar.spbt.webfluxstarter 中新建一个名为: WebfluxStarterApplication 的类，内容为:

@SpringBootApplication
public class WebfluxStarterApplication {

	public static void main(String[] args) {

		SpringApplication.run(WebfluxStarterApplication.class, args);
	}
}

运行程序

启动程序，运行 WebfluxStarterApplication， 将看到系统出现类似如下的反馈:

/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.2.RELEASE)

2019-12-13 08:35:53.692  INFO 47409 --- [           main] c.c.h.s.w.WebfluxStarterApplication      : Starting WebfluxStarterApplication on JinideMacBook-Pro.local with PID 47409 (/Users/jini/Study/Spring/springboot/webflux-starter/target/classes started by jini in /Users/jini/Study/Spring/springboot/webflux-starter)
2019-12-13 08:35:53.696  INFO 47409 --- [           main] c.c.h.s.w.WebfluxStarterApplication      : No active profile set, falling back to default profiles: default
2019-12-13 08:35:55.522  INFO 47409 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data R2DBC repositories in DEFAULT mode.
2019-12-13 08:35:55.551  INFO 47409 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 22ms. Found 0 R2DBC repository interfaces.
2019-12-13 08:35:57.056  INFO 47409 --- [           main] o.s.b.web.embedded.netty.NettyWebServer  : Netty started on port(s): 8080
2019-12-13 08:35:57.061  INFO 47409 --- [           main] c.c.h.s.w.WebfluxStarterApplication      : Started WebfluxStarterApplication in 4.58 seconds (JVM running for 6.573)

注意：这里已经不再是启动 tomcat, 而是直接使用 Netty库了

然后在浏览器中访问:

http://localhost:8080/api/todo

可以看到浏览器中显示:

[{"id":1,"title":"todo1","desc":"desc1"},{"id":2,"title":"todo2","desc":"desc2"}]