使用spring-integration-webflux的dsl实现客户端和服务端流式交互

使用spring-integration-webflux的DSL实现客户端和服务端流式交互需要以下步骤：

1. 引入依赖

在pom.xml文件中引入以下依赖：

<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-webflux</artifactId>
</dependency>

2. 创建服务端

使用WebFlux.fn来创建服务端，示例代码如下：

import org.springframework.http.MediaType;
import org.springframework.integration.dsl.IntegrationFlow;
import org.springframework.integration.dsl.MessageChannels;
import org.springframework.integration.webflux.dsl.WebFlux;
import org.springframework.stereotype.Component;

@Component
public class Server {

    public IntegrationFlow serverFlow() {
        return IntegrationFlows.from(WebFlux.inboundGateway("/stream")
                .requestMapping(m -> m.produces(MediaType.APPLICATION_STREAM_JSON_VALUE))
                .requestPayloadType(String.class))
                .channel(MessageChannels.flux())
                .log()
                .map(String::toUpperCase)
                .map(s -> s + "-stream")
                .get();
    }
}

该方法创建了一个接收客户端请求的WebFlux.inboundGateway，并将请求传递给MessageChannels.flux()通道，接着执行一些转换操作，并返回结果。在示例中，将请求转换为大写并添加后缀“-stream”。

3. 创建客户端

使用WebFlux.fn来创建客户端，示例代码如下：

import org.springframework.http.MediaType;
import org.springframework.integration.dsl.IntegrationFlow;
import org.springframework.integration.dsl.MessageChannels;
import org.springframework.integration.webflux.dsl.WebFlux;
import org.springframework.stereotype.Component;

@Component
public class Client {

    public IntegrationFlow clientFlow() {
        return IntegrationFlows.from(MessageChannels.flux())
                .handle(WebFlux.outboundGateway("http://localhost:8080/stream")
                        .httpMethod(HttpMethod.POST)
                        .expectedResponseType(String.class)
                        .expectedResponseType(MediaType.APPLICATION_STREAM_JSON_VALUE))
                .log()
                .get();
    }
}

该方法从MessageChannels.flux()通道接收请求，并将请求发送到WebFlux.outboundGateway，该网关将请求发送到服务端的“/stream”端点。示例中，期望响应为String类型，MediaType为APPLICATION_STREAM_JSON_VALUE。

4. 创建Spring应用程序

在Spring Boot应用程序的主类中，创建Spring Integration流：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.integration.dsl.IntegrationFlow;

@SpringBootApplication
public class Application {

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

    @Bean
    public IntegrationFlow serverFlow(Server server) {
        return server.serverFlow();
    }

    @Bean
    public IntegrationFlow clientFlow(Client client) {
        return client.clientFlow();
    }
}

5. 测试

启动应用程序并访问http://localhost:8080/stream，应该能看到类似以下的输出：

2019-12-03 16:37:45.947  INFO 6282 --- [ctor-http-nio-2] o.s.integration.handler.LoggingHandler   : GenericMessage [payload=Hello, world!, headers={id=0c9be9f7-191f-8b1a-3f92-12d2c2bd8eaa, contentType=application/json;charset=UTF-8}]
2019-12-03 16:37:45.947  INFO 6282 --- [ctor-http-nio-2] o.s.integration.handler.LoggingHandler   : GenericMessage [payload=HELLO, WORLD!-STREAM, headers={id=dcf0d3c6-9bca-2c39-0f7c-5d5b5db5c5a8, contentType=application/json;charset=UTF-8}]

这表示客户端已成功将请求发送到服务端，并且服务端已成功执行转换操作并将响应发送回客户端。