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1 前言

之前的文章《整合Spring Cloud Stream Binder与RabbitMQ进行消息发送与接收》讲解了Spring Cloud stream与RabbitMQ的整合，本文将简单介绍一下Spring Cloud Stream与Google Cloud Pub/Sub的整合。

2 通过Emulator启动Pub/Sub

因使用实际的GCP Pub/Sub相对麻烦，本文通过模拟器来运行。

关于Google Cloud SDK的安装可参考：Mac安装Google Cloud SDK

安装必要的组件：

gcloud components install beta
gcloud components install pubsub-emulator

启动模拟器：

$ gcloud beta emulators pubsub start --project=pkslow-prj --host-port=0.0.0.0:8511
Executing: /google-cloud-sdk/platform/pubsub-emulator/bin/cloud-pubsub-emulator --host=0.0.0.0 --port=8511
[pubsub] This is the Google Pub/Sub fake.
[pubsub] Implementation may be incomplete or differ from the real system.
[pubsub] May 11, 2021 10:27:31 PM com.google.cloud.pubsub.testing.v1.Main main
[pubsub] INFO: IAM integration is disabled. IAM policy methods and ACL checks are not supported
[pubsub] SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
[pubsub] SLF4J: Defaulting to no-operation (NOP) logger implementation
[pubsub] SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[pubsub] May 11, 2021 10:27:32 PM com.google.cloud.pubsub.testing.v1.Main main
[pubsub] INFO: Server started, listening on 8511

启动的时候设置了项目名和端口。

3 整合

引入依赖：

<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-gcp-pubsub-stream-binder</artifactId>
</dependency>

实现简单的消息收发处理：

package com.pkslow.cloud.stream.binder.pubsub;

@SpringBootApplication
public class StreamBinderPubsub {
    private static final Logger log = LoggerFactory.getLogger(StreamBinderPubsub.class);
    public static void main(String[] args) {
        SpringApplication.run(StreamBinderPubsub.class, args);
    }

    @Bean
    public Supplier<String> pkslowSource() {
        return () -> {
            String message = "www.pkslow.com";
            log.info("Sending value: " + message);
            return message;
        };
    }

    @Bean
    public Consumer<String> pkslowSink() {
        return message -> {
            log.info("Received message " + message);
        };
    }
}

配置Pub/Sub属性与Cloud Stream属性：

spring:
  cloud:
    stream:
      function:
        definition: pkslowSource;pkslowSink
      bindings:
        pkslowSource-out-0:
         destination: pkslow-topic
        pkslowSink-in-0:
          destination: pkslow-topic
      poller:
        fixed-delay: 500
    gcp:
      pubsub:
        emulator-host: localhost:8511
        project-id: pkslow-prj

如果是实际的GCP Pub/Sub，指定key文件即可：

spring:
  cloud:
    gcp:
      credentials:
        location: file:/xxx.json

运行日志如下：

4 总结

代码请查看：https://github.com/LarryDpk/pkslow-samples

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