在Spring WebFlux Web服务中使用Server-Sent Events实现”Hello World”。

这个问题的目标是什么？

我将使用 Windows 11 上的 Linux 进行云开发。

您可以在这里查看文章的列表。

实现

在Ubuntu操作系统上，验证Spring WebFlux应用程序的Server-Sent Events功能。

技术主题

什么是Spring WebFlux？

服务器推送事件 (Server-Sent Events, SSE) 是什么？

开发环境

Windows 11 Home 22H2 を使用しています。

创建Web应用程序的规格

并行处理

创建Spring MVC Web服务

应用程序的功能验证

我們可以從另一個終端窗口使用curl命令來進行確認。

如果获取到一个对象(Map)的情况下。

$ curl -v http://localhost:8080/one -w '\n'
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /one HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Mon, 20 Mar 2023 03:53:45 GMT
<
* Connection #0 to host localhost left intact
{"message":"Hello Object!"}

我会从不同的终端查看日志文件。※ 这里只摘录了必要的部分。

$ cd ~/tmp/sync-spring-mvc/log
$ cat app.log
2023-03-20 13:05:32.679 [INFO ] [main] org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start:220 - Tomcat started on port(s): 8080 (http) with context path ''
2023-03-20 13:05:32.686 [INFO ] [main] org.springframework.boot.StartupInfoLogger.logStarted:61 - Started Application in 0.954 seconds (JVM running for 1.11)
2023-03-20 13:05:45.910 [INFO ] [http-nio-8080-exec-1] org.springframework.web.servlet.FrameworkServlet.initServletBean:525 - Initializing Servlet 'dispatcherServlet'
2023-03-20 13:05:45.913 [INFO ] [http-nio-8080-exec-1] org.springframework.web.servlet.FrameworkServlet.initServletBean:547 - Completed initialization in 1 ms
2023-03-20 13:05:47.930 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.getOne:26 - Sending message: {message=Hello Object!}

如果获取列表

我們將使用curl命令從另一個終端窗口進行驗證。

$ curl -v http://localhost:8080/list -w '\n'
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /list HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200
< Content-Type: application/json
< Transfer-Encoding: chunked
< Date: Mon, 20 Mar 2023 03:56:19 GMT
<
* Connection #0 to host localhost left intact
[{"message":"Hello List 1!"},{"message":"Hello List 2!"},{"message":"Hello List 3!"},{"message":"Hello List 4!"},{"message":"Hello List 5!"}]

我会从另一个终端检查日志文件。※仅提取必要的部分。

$ cd ~/tmp/sync-spring-mvc/log
$ cat app.log
2023-03-20 13:06:34.424 [INFO ] [main] org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start:220 - Tomcat started on port(s): 8080 (http) with context path ''
2023-03-20 13:06:34.430 [INFO ] [main] org.springframework.boot.StartupInfoLogger.logStarted:61 - Started Application in 0.947 seconds (JVM running for 1.102)
2023-03-20 13:06:38.337 [INFO ] [http-nio-8080-exec-1] org.springframework.web.servlet.FrameworkServlet.initServletBean:525 - Initializing Servlet 'dispatcherServlet'
2023-03-20 13:06:38.340 [INFO ] [http-nio-8080-exec-1] org.springframework.web.servlet.FrameworkServlet.initServletBean:547 - Completed initialization in 1 ms
2023-03-20 13:06:40.522 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.lambda$getList$0:45 - Sending message: {message=Hello List 1!}
2023-03-20 13:06:42.691 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.lambda$getList$0:45 - Sending message: {message=Hello List 2!}
2023-03-20 13:06:44.721 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.lambda$getList$0:45 - Sending message: {message=Hello List 3!}
2023-03-20 13:06:46.740 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.lambda$getList$0:45 - Sending message: {message=Hello List 4!}
2023-03-20 13:06:48.748 [INFO ] [http-nio-8080-exec-1] com.example.springmvc.Application.lambda$getList$0:45 - Sending message: {message=Hello List 5!}

总结到这里

异步处理

创建Spring WebFlux Web服务

创建项目文件夹

创建项目文件夹。
※ 将~/tmp/async-spring-webflux设为项目文件夹。

$ mkdir -p ~/tmp/async-spring-webflux
$ cd ~/tmp/async-spring-webflux

创建应用程序类

创建一个应用程序类。

$ mkdir -p src/main/java/com/example/springwebflux
$ vim src/main/java/com/example/springwebflux/Application.java

文件的内容 de

package com.example.springwebflux;

import java.time.Duration;
import java.util.Map;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.codec.ServerSentEvent;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@Slf4j
@CrossOrigin(origins = "*", allowedHeaders = "*")
@RestController
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @GetMapping("/mono")
    public Mono<Map<String, String>> getMono() {
        return Mono.just(
            Map.of("message", "Hello Mono!"))
            .delayElement(Duration.ofSeconds(2))
            .doOnNext(map -> log.info("Sending message: {}", map));
    }

    @GetMapping("/flux")
    public Flux<Map<String, String>> getFlux() {
        return Flux.range(1, 5)
            .map(idx -> Map.of("message", "Hello Flux " + idx + "!"))
            .delayElements(Duration.ofSeconds(2))
            .doOnNext(map -> log.info("Sending message: {}", map));
    }

    @GetMapping("/flux-sse")
    public Flux<ServerSentEvent<Map<String, String>>> getFluxWithSSE() {
        return Flux.range(1, 5)
            .map(idx -> Map.of("message", "Hello Flux " + idx + "!"))
            .delayElements(Duration.ofSeconds(2))
            .doOnNext(map -> log.info("Sending message: {}", map))
            .map(map -> ServerSentEvent.builder(map).build())
            .concatWith(Mono.just(ServerSentEvent.<Map<String, String>>builder().event("end").build()));
    }
}

创建 pom.xml 文件

创建 pom.xml 文件。

$ vim pom.xml

文件的内容 de

<?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>2.7.8</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>sync-spring-webflux</artifactId>
    <version>1.0</version>
    <name>sync-spring-webflux</name>

    <properties>
        <java.version>11</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <!-- Lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.26</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

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

输出日志文件的设置

• application.properties

logback-spring.xml

您可以在这篇相关文章中确认步骤。

应用程序的构建

构建Java应用程序。
※ 将创建目标/app.jar。

$ mvn clean package

打开应用

启动应用程序。
※ 停止应用程序时按下 ctrl + C。

$ rm -rf log
$ mvn spring-boot:run

确认应用的运行情况

我們可以從另一個終端窗口使用curl命令進行確認。

如果以常规方式使用 HTTP 请求 Mono 的情况

$ curl -v http://localhost:8080/mono -w '\n'
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /mono HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Vary: Origin
< Vary: Access-Control-Request-Method
< Vary: Access-Control-Request-Headers
< Content-Type: application/json
< Content-Length: 25
<
* Connection #0 to host localhost left intact
{"message":"Hello Mono!"}

我会从另一个终端查看日志文件。※ 只摘录了必要的部分。

$ cd ~/tmp/async-spring-webflux/log
$ cat app.log
2023-03-20 12:11:59.869 [DEBUG] [main] org.springframework.boot.StartupInfoLogger.logStarting:56 - Running with Spring Boot v2.7.8, Spring v5.3.25
2023-03-20 12:11:59.870 [INFO ] [main] org.springframework.boot.SpringApplication.logStartupProfileInfo:637 - The following 1 profile is active: "develop"
2023-03-20 12:12:00.556 [INFO ] [main] org.springframework.boot.web.embedded.netty.NettyWebServer.start:111 - Netty started on port 8080
2023-03-20 12:12:00.562 [INFO ] [main] org.springframework.boot.StartupInfoLogger.logStarted:61 - Started Application in 0.987 seconds (JVM running for 1.221)
2023-03-20 12:15:32.844 [INFO ] [parallel-1] com.example.springwebflux.Application.lambda$getMono$0:32 - Sending message: {message=Hello Mono!}

如果使用普通的HTTP请求Flux的情况下

我会从另一个终端使用curl命令进行确认。

$ curl -v http://localhost:8080/flux -w '\n'
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /flux HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< transfer-encoding: chunked
< Vary: Origin
< Vary: Access-Control-Request-Method
< Vary: Access-Control-Request-Headers
< Content-Type: application/json
<
* Connection #0 to host localhost left intact
[{"message":"Hello Flux 1!"},{"message":"Hello Flux 2!"},{"message":"Hello Flux 3!"},{"message":"Hello Flux 4!"},{"message":"Hello Flux 5!"}]

我会从另一个终端检查日志文件。※ 我提取了必要的内容。

$ cd ~/tmp/async-spring-webflux/log
$ cat app.log
2023-03-20 12:19:28.477 [INFO ] [main] org.springframework.boot.web.embedded.netty.NettyWebServer.start:111 - Netty started on port 8080
2023-03-20 12:19:28.482 [INFO ] [main] org.springframework.boot.StartupInfoLogger.logStarted:61 - Started Application in 0.95 seconds (JVM running for 1.124)
2023-03-20 12:19:42.389 [INFO ] [parallel-1] com.example.springwebflux.Application.lambda$getFlux$2:40 - Sending message: {message=Hello Flux 1!}
2023-03-20 12:19:44.392 [INFO ] [parallel-2] com.example.springwebflux.Application.lambda$getFlux$2:40 - Sending message: {message=Hello Flux 2!}
2023-03-20 12:19:46.394 [INFO ] [parallel-3] com.example.springwebflux.Application.lambda$getFlux$2:40 - Sending message: {message=Hello Flux 3!}
2023-03-20 12:19:48.396 [INFO ] [parallel-4] com.example.springwebflux.Application.lambda$getFlux$2:40 - Sending message: {message=Hello Flux 4!}
2023-03-20 12:19:50.399 [INFO ] [parallel-5] com.example.springwebflux.Application.lambda$getFlux$2:40 - Sending message: {message=Hello Flux 5!}

如果使用Server-Sent Events指定的HTTP请求Flux的情况下。

从另一个终端使用curl命令进行确认。

$ curl -v http://localhost:8080/flux-sse -H 'Accept: text/event-stream' -w '\n'
*   Trying 127.0.0.1:8080...
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /flux-sse HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.81.0
> Accept: text/event-stream
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< transfer-encoding: chunked
< Vary: Origin
< Vary: Access-Control-Request-Method
< Vary: Access-Control-Request-Headers
< Content-Type: text/event-stream;charset=UTF-8
<
data:{"message":"Hello Flux 1!"}

data:{"message":"Hello Flux 2!"}

data:{"message":"Hello Flux 3!"}

data:{"message":"Hello Flux 4!"}

data:{"message":"Hello Flux 5!"}

event:end

* Connection #0 to host localhost left intact

我要从另一个终端确认日志文件。※仅摘录了必要的部分。

$ cd ~/tmp/async-spring-webflux/log
$ cat app.log
cat app.log
2023-03-20 12:22:02.249 [INFO ] [main] org.springframework.boot.web.embedded.netty.NettyWebServer.start:111 - Netty started on port 8080
2023-03-20 12:22:02.256 [INFO ] [main] org.springframework.boot.StartupInfoLogger.logStarted:61 - Started Application in 1.035 seconds (JVM running for 1.224)
2023-03-20 12:22:17.814 [INFO ] [parallel-1] com.example.springwebflux.Application.lambda$getFluxWithSSE$4:48 - Sending message: {message=Hello Flux 1!}
2023-03-20 12:22:19.827 [INFO ] [parallel-2] com.example.springwebflux.Application.lambda$getFluxWithSSE$4:48 - Sending message: {message=Hello Flux 2!}
2023-03-20 12:22:21.831 [INFO ] [parallel-3] com.example.springwebflux.Application.lambda$getFluxWithSSE$4:48 - Sending message: {message=Hello Flux 3!}
2023-03-20 12:22:23.842 [INFO ] [parallel-4] com.example.springwebflux.Application.lambda$getFluxWithSSE$4:48 - Sending message: {message=Hello Flux 4!}
2023-03-20 12:22:25.854 [INFO ] [parallel-5] com.example.springwebflux.Application.lambda$getFluxWithSSE$4:48 - Sending message: {message=Hello Flux 5!}

这是目前为止的总结。

仅提供一种选项：
总结

我能够在使用Ubuntu搭建的简单Java开发环境下，运行实现了Server-Sent Events的Spring WebFlux Web服务。

请问感觉怎么样？在 WSL Ubuntu 上，您可以轻松运行实现 Server-Sent Events 的 Spring Boot Web 应用程序。请务必尝试一下。我们将继续介绍Java开发环境等内容，请敬请期待。

请提供相关参考资料。

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