springcloud的stream消息组件的使用@StreamListener

常见问题（使用rabbitmq）

消息分组防止多实例重复消费
在一个服务多实例场景下使用默认使用@StreamListener监听消息消费，yml中没有特殊配置的话是会导致消息重复消费的，原因是此时每个实例都是匿名在rabbitmq上注册的队列，需要给消费者指定一个消费组，让消息在组里只被消费一次；

spring.cloud.stream.bindings.xxx(消费者队列名).group=xxx(组名)

在springboot下在同一个服务（项目中）使用@input和@outPut时指定的队列名是不可以重复的.会在启动编译的时候报bean定义重复。需要在yml给生产者和消费者指定同一个交换机。

spring:
  rabbitmq:
    host: xxx.xxx.xxx.xx
    port: 35672
    username: xxx
    password: xxx
    virtual-host: /xxx
  cloud:
    stream:
      bindings:
        in:
          #若消息系统是RabbitMQ，目的地（destination）就是指exchange，消息系统是Kafka，那么就是指topic
          destination: test
          #在多实例的时候需要制定一个消息分组，不然每个实例都是匿名方式把队列注册到rabbitmq上去，导致一个交换机下有多个队列
          #并且默认生成的交换机是topic类型的，会导致重复消费
          group: myIn
        out:
          destination: test

先上依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0modelVersion>
    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.5.8.RELEASEversion>
        <relativePath/> 
    parent>
    <groupId>com.fchangroupId>
    <artifactId>springcloudstreamartifactId>
    <version>0.0.1-SNAPSHOTversion>
    <name>springcloudstreamname>
    <description>Demo project for Spring Bootdescription>
    <properties>
        <java.version>1.8java.version>
    properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starterartifactId>
        dependency>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-testartifactId>
            <scope>testscope>
        dependency>

        <dependency>
            <groupId>org.springframework.cloudgroupId>
            <artifactId>spring-cloud-starter-stream-rabbitartifactId>

        dependency>

        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-actuatorartifactId>
        dependency>

    dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloudgroupId>
                <artifactId>spring-cloud-stream-dependenciesartifactId>
                <version>Ditmars.RELEASEversion>
                <type>pomtype>
                <scope>importscope>
            dependency>
        dependencies>
    dependencyManagement>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-maven-pluginartifactId>
            plugin>
        plugins>
    build>

project>

再上yml配置

spring:
  rabbitmq:
    host: xxx.xxx.xxx.xx
    port: 35672
    username: xxx
    password: xxx
    virtual-host: /xxx
  cloud:
    stream:
      bindings:
        in:
          #若消息系统是RabbitMQ，目的地（destination）就是指exchange，消息系统是Kafka，那么就是指topic
          destination: test
          #在多实例的时候需要制定一个消息分组，不然每个实例都是匿名方式把队列注册到rabbitmq上去，导致一个交换机下有多个队列
          #并且默认生成的交换机是topic类型的，会导致重复消费
          group: myIn
        out:
          destination: test

消息生产者

package com.fchan.springcloudstream.service;

import org.springframework.cloud.stream.annotation.Input;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.SubscribableChannel;

public interface MyMessageChannel {

    String out = "out";
    String in = "in";

    @Output(out)
    MessageChannel out();


    @Input(in)
    SubscribableChannel in();


}

发送消息

package com.fchan.springcloudstream.controller;

import com.fchan.springcloudstream.service.MyMessageChannel;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.HashMap;
import java.util.Map;

@RestController
public class MessageController {

    @Resource
    private MyMessageChannel myMessageChannel;


    @RequestMapping("test")
    public String testMessage(){
        Map<String,Object> map = new HashMap<>();
        map.put("shopId", "123");
        myMessageChannel.out().send(MessageBuilder.withPayload(map).build());
        return "success";
    }



}

消息消费者

package com.fchan.springcloudstream.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.messaging.Message;
import org.springframework.stereotype.Component;

import java.util.Map;

@Component
@EnableBinding({MyMessageChannel.class})
public class MyConsumer {

    Logger log = LoggerFactory.getLogger(MyConsumer.class);


    @StreamListener(MyMessageChannel.in)
    public void input(Message<Map<String,Object>> message){
        log.info("收到消息：{}", message.getPayload());
    }

}