十一、springCloud之stream

屏蔽底层消息中间的操作

新建消息提供者：

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-stream-rabbit</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.smy.springcloud</groupId>
            <artifactId>common-api</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>

yml配置：

server:
  port: 8801
spring:
  application:
    name: STREAM-RABBITMQ-PROVIDER
  cloud:
    stream:
      binders:
        defaultRabbit:
          type: rabbit
          environment:
            spring:
              rabbitmq:
                host: 127.0.0.1
                port: 5672
                username: guest
                password: guest
      bindings:
        output:
          destination: studyExchange
          content-type: application/json
          binder: defaultRabbit


eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://peer1:7001/eureka,http://peer2:7002/eureka
  instance:
    instance-id: stream-rabbitmq-8801
    prefer-ip-address: true
    lease-renewal-interval-in-seconds: 1
    lease-expiration-duration-in-seconds: 2

主类：

@SpringBootApplication
@EnableEurekaClient
public class StreamRabbutmqMain8801 {
    public static void main(String[] args) {
        SpringApplication.run(StreamRabbutmqMain8801.class,args);
    }
}

具体的提供逻辑：注意包的引入

package com.xx.service.impl;

import cn.hutool.core.lang.UUID;
import com.smy.service.IMessageItf;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.messaging.Source;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.messaging.MessageChannel;

import javax.annotation.Resource;

/**
 * @author: xx
 * @createDate: 2020/9/4 7:08
 */
@EnableBinding(Source.class)  //定义消息的推送管道
public class IMessageImpl implements IMessageItf {
    @Resource
    private MessageChannel output;
    @Override
    public String send() {
        String uuid = UUID.randomUUID().toString();
        output.send(MessageBuilder.withPayload(uuid).build());
        System.out.println("提供消息："+uuid);
        return uuid;
    }
}

controller:

@RestController
public class IMessageController {
    @Resource
    private IMessageItf iMessageItf;
    @GetMapping("/sendMessage")
    public String sendMessage(){
        return iMessageItf.send();
    }
}

消费方构建：pom和主类与提供方一样

yml配置：

server:
  port: 8802
spring:
  application:
    name: STREAM-RABBITMQ-CONSOMER
  cloud:
    stream:
      binders:
        defaultRabbit:
          type: rabbit
          environment:
            spring:
              rabbitmq:
                host: 127.0.0.1
                port: 5672
                username: guest
                password: guest
      bindings:
        input:
          destination: studyExchange
          content-type: application/json
          binder: defaultRabbit


eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://peer1:7001/eureka,http://peer2:7002/eureka
  instance:
    instance-id: stream-rabbitmq-8802
    prefer-ip-address: true
    lease-renewal-interval-in-seconds: 1
    lease-expiration-duration-in-seconds: 2

controller：

@Component
@EnableBinding(Sink.class)
public class StreamListenerController {
    @StreamListener(Sink.INPUT)
    public void input(Message<String> message){
        System.out.println("消息："+message.getPayload());
    }
}

请求提供方的地址：http://127.0.0.1:8801/sendMessage    好完成最简单的提供和订阅。

重复消费，消息持久化。

重复消费问题：同一个组内会发生竞争关系，消息只会被消费一次。

不同的组会存在重复消费的问题。下面是两个组的示例。

解决重复消费就要分组添加配置yml文件group: xxx

持久化：当有服务添加group分组信息，消息消费服务停机重启会自动拉去在这段时间未消费的消息。

spring:
  application:
    name: STREAM-RABBITMQ-CONSOMER
  cloud:
    stream:
      binders:
        defaultRabbit:
          type: rabbit
          environment:
            spring:
              rabbitmq:
                host: 127.0.0.1
                port: 5672
                username: guest
                password: guest
      bindings:
        input:
          destination: studyExchange
          content-type: application/json
          binder: defaultRabbit
          group: rabbitmqA