Java 如何在SpringCloudStream中配置函数的绑定，将其输入绑定到web端点，将其输出绑定到Kafka主题

我有一个常规的java

函数

；我正试图将其绑定：

将其输入到web端点

将其输出为卡夫卡主题 当我在web上下文中使用我的函数时，它总是将

函数的结果值

单独返回给web客户端。我可以这样做吗

spring.cloud.stream.bindings.input.binder=web
spring.cloud.stream.bindings.output.binder=kafka

我目前甚至正在尝试将

函数

分为两部分：

• 其输入绑定到web客户端，其输出动态绑定到第二个函数（使用

  spring.cloud.stream.sendto.destination

  ）
• 另一个函数，其输出绑定到kafka绑定

但这种方法也不起作用。动态路由（

spring.cloud.stream.sendto.destination

）显示在web客户端上；但是没有

消息

发送到卡夫卡绑定本身。下面是我在第二种方法（2个函数）中使用的代码，希望得到一个Spring函数应用程序，将其输入绑定到web端点，并将输出绑定到kafka主题

WebToKafkaApp.java

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

    @Bean
    public Function<String, Message<String>> webFunction() {
        return payload -> createPayloadMapperToMessage("kafkaFunction").apply(payload);
    }

    @Bean
    public Function<Flux<Message<String>>, Flux<Message<String>>> kafkaFunction() {
        return flux -> flux.map(msg -> createPayloadMapperToMessage("").apply(msg.getPayload()));
    }

    private Function<String, Message<String>> createPayloadMapperToMessage(String destination) {
        return payload -> MessageBuilder
                .withPayload(payload.toUpperCase())
                .setHeader("spring.cloud.stream.sendto.destination", destination)
                .build();
    }
}

build.gradle

plugins {
    id 'org.springframework.boot' version '2.2.1.RELEASE'
    id 'io.spring.dependency-management' version '1.0.8.RELEASE'
    id 'java'
}
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'
repositories {
    mavenCentral()
}
ext {
    set('springCloudVersion', "Hoxton.RELEASE")
}
dependencies {
    implementation 'org.springframework.boot:spring-boot-starter'
    implementation 'org.springframework.cloud:spring-cloud-starter-function-web'
    implementation 'org.springframework.cloud:spring-cloud-starter-function-webflux'
    implementation 'org.springframework.cloud:spring-cloud-stream'
    implementation 'org.springframework.cloud:spring-cloud-starter-stream-kafka'
    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }
}
dependencyManagement {
    imports {
        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
    }
}
test {
    useJUnitPlatform()
}

任何帮助都将不胜感激。

感谢您的发布。基本上，我强化了他的建议，即一般性地处理以下两者之间的桥梁：

功能性web控制器；它可以接收web请求

流供应商；它可以将任何消息转发到消息传递基础结构

此解决方案将中描述的问题封装在

供应商的自定义实现中。这样的实现公开了一个API来触发供应商发出作为参数传递的消息。这样的类将如下所示：

import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

import java.util.function.Supplier;

import reactor.core.publisher.EmitterProcessor;
import reactor.core.publisher.Flux;

public class StreamSupplier implements Supplier<Flux<?>> {

    private static final String SPRING_CLOUD_STREAM_SENDTO_DESTINATION =
            "spring.cloud.stream.sendto.destination";

    public static <T> Message<?> createMessage(T payload, String destination) {
        MessageBuilder<T> builder = MessageBuilder.withPayload(payload);
        if (destination != null && !destination.isEmpty())
            builder.setHeader(SPRING_CLOUD_STREAM_SENDTO_DESTINATION, destination);
        return builder.build();
    }

    private String defaultDestination;
    private EmitterProcessor<? super Object> processor = EmitterProcessor.create();

    public StreamSupplier() {
        this(null);
    }

    public StreamSupplier(String defaultDestination) {
        this.defaultDestination = defaultDestination;
    }

    // SEND APIs

    public <T> Message<?> sendMessage(T payload) {
        return sendMessage(payload, defaultDestination);
    }

    public <T> Message<?> sendMessage(T payload, String destination) {
        return sendBody(createMessage(payload, destination));
    }

    public <T> T sendBody(T body) {
        processor.onNext(body);
        return body;
    }

    /**
     * Returns {@link EmitterProcessor} used internally to programmatically publish messages onto
     * the output binding associated with this {@link Supplier}. Such programmatic publications
     * are available through the {@code sendXXX} API methods available in this class.
     */
    @Override
    public Flux<?> get() {
        return processor;
    }
}

再次感谢您为我提供了构建此综合解决方案所需的资源

请在感谢@OlegZhurakousky为我指明了正确的方向中查看答案。我只是通过在您的细节之上构建额外的抽象级别来回答我的问题。
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;

import java.util.function.Supplier;

import reactor.core.publisher.EmitterProcessor;
import reactor.core.publisher.Flux;

public class StreamSupplier implements Supplier<Flux<?>> {

    private static final String SPRING_CLOUD_STREAM_SENDTO_DESTINATION =
            "spring.cloud.stream.sendto.destination";

    public static <T> Message<?> createMessage(T payload, String destination) {
        MessageBuilder<T> builder = MessageBuilder.withPayload(payload);
        if (destination != null && !destination.isEmpty())
            builder.setHeader(SPRING_CLOUD_STREAM_SENDTO_DESTINATION, destination);
        return builder.build();
    }

    private String defaultDestination;
    private EmitterProcessor<? super Object> processor = EmitterProcessor.create();

    public StreamSupplier() {
        this(null);
    }

    public StreamSupplier(String defaultDestination) {
        this.defaultDestination = defaultDestination;
    }

    // SEND APIs

    public <T> Message<?> sendMessage(T payload) {
        return sendMessage(payload, defaultDestination);
    }

    public <T> Message<?> sendMessage(T payload, String destination) {
        return sendBody(createMessage(payload, destination));
    }

    public <T> T sendBody(T body) {
        processor.onNext(body);
        return body;
    }

    /**
     * Returns {@link EmitterProcessor} used internally to programmatically publish messages onto
     * the output binding associated with this {@link Supplier}. Such programmatic publications
     * are available through the {@code sendXXX} API methods available in this class.
     */
    @Override
    public Flux<?> get() {
        return processor;
    }
}

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Controller;

import java.util.function.Function;
import java.util.function.Supplier;

import reactor.core.publisher.Flux;

@SpringBootApplication
@Controller
public class MyApp {

    public static void main(String[] args) {
        SpringApplication.run(MyApp.class,
                "--spring.cloud.function.definition=streamSupplierFunction;webToStreamFunction");
    }

    // Functional Web Controller
    @Bean
    public Function<String, String> webToStreamFunction() {
        return msg -> streamSupplier().sendBody(msg);
    }

    // Functional Stream Supplier
    @Bean
    public Supplier<Flux<?>> streamSupplierFunction() {
        return new StreamSupplier();
    }

    // DOUBLE REGISTRATION TO AVOID POLLABLE CONFIGURATION
    // LIMITATION OF SPRING-CLOUD-FUNCTION
    @Bean
    public StreamSupplier streamSupplier() {
        return (StreamSupplier) streamSupplierFunction();
    }
}