【SpringCloud】这一次终于使用MQ解决了Eureka服务下线延迟感知问题

@Component
public class EurekaEventToRabbitMQPublisher {
 
    private static final Logger LOGGER = LoggerFactory.Logger(EurekaEventToRabbitMQPublisher.class);
 
    @Autowired
    private RabbitTemplate rabbitTemplate;
 
    @Autowired
    private ObjectMapper objectMapper;
 
    @Autowired
    private Environment environment;
 
    @Autowired
    private DiscoveryClient discoveryClient;
 
    @RabbitListener(queues = "#{T(com.netflix.appinfo.InstanceInfo).InstanceStatus.DOWN}")
    public void handleInstancesChangeEvent(Message message) {
        try {
            InstanceInfo instanceInfo = objectMapper.readValue(new String((byte[]) message.getPayload()), InstanceInfo.class);
            String serviceId = instanceInfo.getAppName();
            List<ServiceInstance> instances = discoveryClient.getInstances(serviceId);
            if (instances.isEmpty()) {
                rabbitTemplate.convertAndSend(environment.getProperty("spring.rabbitmq.exchange"), 
                                              serviceId, instanceInfo.getAppName());
            }
        } catch (Exception e) {
            LOGGER.error("处理Eureka服务下线事件异常：", e);
        }
    }
}

这段代码示例展示了如何使用RabbitMQ来替代Eureka的服务下线延迟感知问题。通过定义一个RabbitMQ的监听器来处理服务下线事件，并且只有在服务实例列表为空时，才发送一个消息到RabbitMQ交换器。这样就可以避免Eureka服务器的下线延迟问题，实现即时的服务状态感知。