学习笔记:微服务15 spring cloud kafka 消息总线

在比如限时抢购，车票抢购，选课排队等许多场景，都需要消息总线，在spring cloud生态圈中，多个微服务协同工作，多对多处理交付任务和处理任务排队，需要实现消息总线，

本例采用kafka 作为消息服务器，以下代码从网上复制，经调试通过。

1. 依赖

   <dependency>
   <groupId>org.springframework.kafka</groupId>
   <artifactId>spring-kafka</artifactId>
   </dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
</dependency>

2. 定义消息类

@Data
public class Message {
private Long id;//id
private String msg; //消息
private Date sendTime; //发送时间
   public void setId(Long i) {
       this.id=i;
   }
   public Long getId() {
   return this.id;
   }
   public void setMsg(String string) {
       this.msg=string;
   }
   public String getMsg() {
       return this.msg;
   }
   public void setSendTime(Date date) {
       this.sendTime=date;
   }
   public Date getSendTime() {
       return this.sendTime;
   }
}

3. 发送消息类（生产者）

@Component
@Slf4j
public class KafkaSender {
@Autowired
private KafkaTemplate<String,String> kafkaTemplate;

private Gson gson = new GsonBuilder().create();

   public void send(Long i){
   Message message = new Message();
   message.setId(i);
   message.setMsg(UUID.randomUUID().toString());
   message.setSendTime(new Date());
   System.out.printf("========发送消息 "+i+" >>>>{}<<<<<==========",gson.toJson(message));
   kafkaTemplate.send("linbin",gson.toJson(message));
   }
}

4. 消费消息类（接收者）

@Component
@Slf4j
public class KafkaConsumer {

@KafkaListener(topics = {"linbin"})
public void consumer(ConsumerRecord<?,?> consumerRecord){
//判断是否为null
Optional<?> kafkaMessage = Optional.ofNullable(consumerRecord.value());
System.out.printf(">>>>>>>>>> record =" + kafkaMessage);
if(kafkaMessage.isPresent()){
//得到Optional实例中的值
Object message = kafkaMessage.get();
System.out.printf(">>>>>>>>接收消息message =" + message);
}
}
}

5. application.propties 配置

server.port: 8807
spring.application.name=MicroserviceKafkaDemo8807
eureka.client.serviceUrl.defaultZone=http://admin:[email protected]:8101/eureka/,http://admin:[email protected]:8102/eureka/

#============== kafka ===================
spring.kafka.bootstrap-servers=centos7.linbsoft.com:9092
#=============== provider =======================
spring.kafka.producer.retries=0
spring.kafka.producer.batch-size=16384
spring.kafka.producer.buffer-memory=33554432
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer
#=============== consumer =======================
spring.kafka.consumer.group-id=test-consumer-group
spring.kafka.consumer.auto-offset-reset=earliest
spring.kafka.consumer.enable-auto-commit=true //能自动检测有无消息到来
spring.kafka.consumer.auto-commit-interval=100 //设置检测消息的间隔
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer

6.启动类

@SpringBootApplication
public class MicroserviceKafkaDemo8807Application {

   @Autowired
   private KafkaSender kafkaSender;
   @PostConstruct
   public void init(){
   for (int i = 0; i < 10; i++) {
   //调用消息发送类中的消息发送方法
   kafkaSender.send((long) i);
   }
   }
   public static void main(String[] args) {
       SpringApplication.run(MicroserviceKafkaDemo8807Application.class, args);
   }
}

7.测试，启动项目即可

在初始化启动时，会发送10次消息，因为会自动间隔查询接受消息，也可以在控制台看到接收消息，在实际应用中，发送消息和接收消息的可能是不同的微服务

以下是控制台输出


>>>>>>>>>> record =Optional[{"id":0,"msg":"52e2c325-fb09-4850-8ab3-e7094a0dca26","sendTime":"Jan 2, 2019 10:08:39 PM"}]
>>>>>>>>接收消息message ={"id":0,"msg":"52e2c325-fb09-4850-8ab3-e7094a0dca26","sendTime":"Jan 2, 2019 10:08:39 PM"}
>>>>>>>>>> record =Optional[{"id":1,"msg":"3803c445-dbff-477a-a4c9-bef4656b2db4","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":1,"msg":"3803c445-dbff-477a-a4c9-bef4656b2db4","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":2,"msg":"27b149dc-90cd-4877-8366-bb48e177b9b7","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":2,"msg":"27b149dc-90cd-4877-8366-bb48e177b9b7","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":3,"msg":"7b5b12ce-9a05-41c1-a0db-a07fb496884b","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":3,"msg":"7b5b12ce-9a05-41c1-a0db-a07fb496884b","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":4,"msg":"a653dc4c-4a1b-4b1d-a6cb-2f2cdf4b1854","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":4,"msg":"a653dc4c-4a1b-4b1d-a6cb-2f2cdf4b1854","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":5,"msg":"2e64259f-c02c-4719-8fef-49619fbb1b9a","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":5,"msg":"2e64259f-c02c-4719-8fef-49619fbb1b9a","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":6,"msg":"93682e0a-5464-4c5f-a46a-53e48380eccf","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":6,"msg":"93682e0a-5464-4c5f-a46a-53e48380eccf","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":7,"msg":"bbf6098b-7bf1-4336-a1ed-ac2d0a2d4a94","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":7,"msg":"bbf6098b-7bf1-4336-a1ed-ac2d0a2d4a94","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":8,"msg":"c0eb6f38-6042-4f54-8379-de6f7d50c8a8","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":8,"msg":"c0eb6f38-6042-4f54-8379-de6f7d50c8a8","sendTime":"Jan 2, 2019 10:08:45 PM"}
>>>>>>>>>> record =Optional[{"id":9,"msg":"e16e6d93-7574-493f-a166-50077f868662","sendTime":"Jan 2, 2019 10:08:45 PM"}]
>>>>>>>>接收消息message ={"id":9,"msg":"e16e6d93-7574-493f-a166-50077f868662","sendTime":"Jan 2, 2019 10:08:45 PM"}

测试完毕

学习笔记:微服务15 spring cloud kafka 消息总线

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