如何使用 spring 集成实现 POST http 端点？

【问题标题】：How to implement POST http endpoint using spring integration?如何使用 spring 集成实现 POST http 端点？
【发布时间】：2019-08-28 13:16:53
【问题描述】：

我有以下配置：

@Configuration
@EnableIntegration
@IntegrationComponentScan
public class Config {

    @Bean
    public IntegrationFlow integrationFlow() {
        return IntegrationFlows.from(Http.inboundGateway("/spring_integration_post")
                .requestMapping(m -> m.methods(HttpMethod.POST))
                .requestPayloadType(String.class)
        ).channel("responseChannel")
                .get();
    }
}

但是当请求时，我在服务器端看到以下日志：

org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:138) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:401) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:166) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:47) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:109) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutput(AbstractMessageProducingHandler.java:431) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.doProduceOutput(AbstractMessageProducingHandler.java:284) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.produceOutput(AbstractMessageProducingHandler.java:265) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageProducingHandler.sendOutputs(AbstractMessageProducingHandler.java:223) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:129) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:169) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:115) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:132) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:105) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:73) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.channel.AbstractMessageChannel.send(AbstractMessageChannel.java:453) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:187) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSendAndReceive(GenericMessagingTemplate.java:233) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.GenericMessagingTemplate.doSendAndReceive(GenericMessagingTemplate.java:47) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.messaging.core.AbstractMessagingTemplate.sendAndReceive(AbstractMessagingTemplate.java:46) ~[spring-messaging-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.integration.core.MessagingTemplate.sendAndReceive(MessagingTemplate.java:97) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.gateway.MessagingGatewaySupport.doSendAndReceive(MessagingGatewaySupport.java:499) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.gateway.MessagingGatewaySupport.sendAndReceiveMessage(MessagingGatewaySupport.java:470) ~[spring-integration-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingEndpointSupport.actualDoHandleRequest(HttpRequestHandlingEndpointSupport.java:362) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingEndpointSupport.doHandleRequest(HttpRequestHandlingEndpointSupport.java:253) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.integration.http.inbound.HttpRequestHandlingMessagingGateway.handleRequest(HttpRequestHandlingMessagingGateway.java:112) ~[spring-integration-http-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:53) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

我不知道我应该在哪里订阅。如何编写请求处理程序来处理请求并准备响应？

【问题讨论】：

  • 您需要显示从“responseChannel”消耗的流的配置 - 听起来您那里什么都没有（或错误在下游）。
  • @Gary Russell 我真的什么都没有

标签： java spring-integration spring-integration-dsl spring-integration-http


【解决方案1】：

首先，您似乎不需要@IntegrationComponentScan。这个特别适用于@MessagingGateway 解析。如果您不使用此类网关，请考虑将其删除。文档中的更多信息：https://docs.spring.io/spring-integration/docs/5.2.0.BUILD-SNAPSHOT/reference/html/gateway.html#messaging-gateway-annotation

Dispatcher has no subscribers 明确表示有一些 DirectChannel bean，而这个在任何地方都没有用作订阅的 inputChannel，例如通过@ServiceActivator 或IntegrationFlows.from()。

查看您提供的代码，感觉就像您的 .channel("responseChannel") 没有任何下游处理。

你需要习惯 EIP 原则，并自己确定 Spring Integration 中的所有内容都是通过通道连接的，但有时如果另一端丢失（或停止），你将有这样的异常，因为没有办法发送并忘记：DirectChannel 仅用于 EIP 语义，所有内容都在同一个线程上调用，就像在普通 Java 代码流中一样。

【讨论】：

  • 你能列出我除了stackoverflow.com/a/57693946/2674303之外的选项吗？
  • 如您所见，我发现handle方法可以处理请求并将其返回转换为响应并发送回客户端
  • 对，但是你错过了Http.inboundGateway() 和.handle() 之间存在隐含通道的事实。这就是您订阅的地方。您可以做类似的事情，将您的.channel("responseChannel") 留在代码中，然后添加.handle()。另一种方法是再拥有一个IntegrationFlow bean，它可以从`IntegrationFlows.from("responseChannel")` 开始，然后再以handle() 开始。我的问题是我无法确定您将如何处理消息，因为问题中没有您的自定义代码。因此，我的回答中没有任何内容。
【解决方案2】：

最终我能够解决问题：

@Configuration
@EnableIntegration
public class Config {

    @Bean
    public IntegrationFlow integrationFlow() {
        return IntegrationFlows.from(Http.inboundGateway("/spring_integration_post")
                .requestMapping(m -> m.methods(HttpMethod.POST))
                .requestPayloadType(String.class))
                .handle((GenericHandler<String>) (payload, headers) -> "SERVER " + payload)
                .get();
    }
}

【讨论】：

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