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spring-integration:如何从WebFlux集成流创建Spring Reactor Flux?

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How to create a Spring Reactor Flux from Http integration flow? artem-bilan mentioned in a comment中,将来可以使用webflux集成 .

从撰写评论的时间开始,WebFlux集成已经factored out to spring-integration-webflux . 我已尝试以下方法通过使用 WebFlux.inboundChannelAdapterWebFlux.inboundGateway 替换MVC版本的 Http.inboundChannelAdapter@GetRequest 处理程序来复制基于MVC的http-> flux与基于WebFlux的集成:

@SpringBootApplication
public class WebfluxApplication {

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


  @Bean
  public Publisher<Message<String>> reactiveSource() {
    return IntegrationFlows.
            from(WebFlux.inboundChannelAdapter("/message/{id}")
                    .requestMapping(r -> r
                            .methods(HttpMethod.POST)
                    )
                    .payloadExpression("#pathVariables.id")
            )
            .log()
            .channel(MessageChannels.flux())
            .toReactivePublisher();
  }


  @Bean
  public IntegrationFlow eventMessages() {
    return IntegrationFlows
            .from(WebFlux.inboundGateway("/events")
                    .requestMapping(m -> m.produces(MediaType.TEXT_EVENT_STREAM_VALUE)))
            .handle((p, h) -> reactiveSource())                
            .get();
}

}

看来 reactiveSource() 发布者中的流没有收到任何消息,至少没有记录我的 .log() 语句 .

当我在 eventMessages 流程中替换 reactiveSource() 发布者时

.handle((p, h) -> reactiveSource())

由一个假的出版商

.handle((p, h) -> Flux.just("foo", "bar"))

我得到了SSE回复

curl localhost:8080/events

跟踪日志显示 reactiveSource() POST处理程序已映射,并且正在调用 WebFluxInboundEndpoint.handle 方法:

2018-05-05 16:50:58.788  INFO 6552 --- [           main] xIntegrationRequestMappingHandlerMapping : Mapped "{[/message/{id}],methods=[POST]}" onto public abstract reactor.core.publisher.Mono<java.lang.Void> org.springframework.web.server.WebHandler.handle(org.springframework.web.server.ServerWebExchange)
2018-05-05 16:50:58.789  INFO 6552 --- [           main] xIntegrationRequestMappingHandlerMapping : Mapped "{[/events],methods=[GET || POST],produces=[text/event-stream]}" onto public abstract reactor.core.publisher.Mono<java.lang.Void> org.springframework.web.server.WebHandler.handle(org.springframework.web.server.ServerWebExchange)
2018-05-05 16:50:59.191  INFO 6552 --- [ctor-http-nio-1] r.ipc.netty.tcp.BlockingNettyContext     : Started HttpServer on /0:0:0:0:0:0:0:0:8080
2018-05-05 16:50:59.192  INFO 6552 --- [           main] o.s.b.web.embedded.netty.NettyWebServer  : Netty started on port(s): 8080
2018-05-05 16:50:59.196  INFO 6552 --- [           main] d.e.sample.webflux.WebfluxApplication    : Started WebfluxApplication in 2.608 seconds (JVM running for 3.419)
2018-05-05 16:51:06.918 DEBUG 6552 --- [ctor-http-nio-2] o.s.web.reactive.DispatcherHandler       : Processing POST request for [http://localhost:8080/message/4]
2018-05-05 16:51:06.932 DEBUG 6552 --- [ctor-http-nio-2] s.w.r.r.m.a.RequestMappingHandlerMapping : Looking up handler method for path /message/4
2018-05-05 16:51:06.933 DEBUG 6552 --- [ctor-http-nio-2] s.w.r.r.m.a.RequestMappingHandlerMapping : Did not find handler method for [/message/4]
2018-05-05 16:51:06.967 TRACE 6552 --- [ctor-http-nio-2] o.s.w.r.r.method.InvocableHandlerMethod  : Invoking 'org.springframework.integration.webflux.inbound.WebFluxInboundEndpoint.handle' with arguments [org.springframework.web.server.adapter.DefaultServerWebExchange@775cdb20]
2018-05-05 16:51:06.967 TRACE 6552 --- [ctor-http-nio-2] o.s.w.r.r.method.InvocableHandlerMethod  : Method [org.springframework.integration.webflux.inbound.WebFluxInboundEndpoint.handle] returned [MonoDefer]
2018-05-05 16:51:06.967 DEBUG 6552 --- [ctor-http-nio-2] o.s.w.r.r.method.InvocableHandlerMethod  : Response fully handled in controller method
2018-05-05 16:51:11.363 DEBUG 6552 --- [ctor-http-nio-3] o.s.web.reactive.DispatcherHandler       : Processing POST request for [http://localhost:8080/message/4]
2018-05-05 16:51:11.363 DEBUG 6552 --- [ctor-http-nio-3] s.w.r.r.m.a.RequestMappingHandlerMapping : Looking up handler method for path /message/4
2018-05-05 16:51:11.363 DEBUG 6552 --- [ctor-http-nio-3] s.w.r.r.m.a.RequestMappingHandlerMapping : Did not find handler method for [/message/4]
2018-05-05 16:51:11.364 TRACE 6552 --- [ctor-http-nio-3] o.s.w.r.r.method.InvocableHandlerMethod  : Invoking 'org.springframework.integration.webflux.inbound.WebFluxInboundEndpoint.handle' with arguments [org.springframework.web.server.adapter.DefaultServerWebExchange@71f648a3]
2018-05-05 16:51:11.364 TRACE 6552 --- [ctor-http-nio-3] o.s.w.r.r.method.InvocableHandlerMethod  : Method [org.springframework.integration.webflux.inbound.WebFluxInboundEndpoint.handle] returned [MonoDefer]
2018-05-05 16:51:11.364 DEBUG 6552 --- [ctor-http-nio-3] o.s.w.r.r.method.InvocableHandlerMethod  : Response fully handled in controller method

这是为什么?

1 回答

  • 1

    原因似乎是WebFluxInboundEndpoint在 doHandle() (行)中停止处理没有正文的POST请求

    .map(body -> new HttpEntity<>(...))
    

    如果没有请求正文内容,则永远不会执行:

    private Mono<Void> doHandle(ServerWebExchange exchange) {
        return extractRequestBody(exchange)
                .doOnSubscribe(s -> this.activeCount.incrementAndGet())
                .map(body -> new HttpEntity<>(body, exchange.getRequest().getHeaders()))
                .map(entity -> buildMessage(entity, exchange))
                .flatMap(requestMessage -> {
                    if (this.expectReply) {
                        return sendAndReceiveMessageReactive(requestMessage)
                                .flatMap(replyMessage -> populateResponse(exchange, replyMessage));
                    }
                    else {
                        send(requestMessage);
                        return setStatusCode(exchange);
                    }
                })
                .doOnTerminate(this.activeCount::decrementAndGet);
    
    }
    

    解决方法:调用者必须发送任何非空的请求主体才能使其正常工作,例如用-d传递的单引号就足够了:

    curl -d ' http://localhost:8080/message/4
    

    有了这样的请求,我的日志包含预期的传入GenericMessage,并且/ events资源开始生成SSE .

    2018-05-05 17:25:24.777 TRACE 40436 --- [ctor-http-nio-8] o.s.w.r.r.method.InvocableHandlerMethod  : Method [org.springframework.integration.webflux.inbound.WebFluxInboundEndpoint.handle] returned [MonoDefer]
    2018-05-05 17:25:24.777 DEBUG 40436 --- [ctor-http-nio-8] o.s.w.r.r.method.InvocableHandlerMethod  : Response fully handled in controller method
    2018-05-05 17:25:24.778  INFO 40436 --- [ctor-http-nio-8] o.s.integration.handler.LoggingHandler   : GenericMessage [payload=4, headers={http_requestMethod=POST, Accept=*/*, User-Agent=curl/7.49.1, http_requestUrl=http://localhost:8080/message/4, Host=localhost:8080, id=9a09294d-280a-af3b-0894-23597cf1cb5f, Content-Length=1, contentType=application/x-www-form-urlencoded, timestamp=1525533924778}]
    

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