微服務可以在“自己的程式”中執行，並通過“輕量級裝置與HTTP型API進行溝通”。這裡的溝通就是本節要說的服務間通訊。即各個微服務註冊到Eureka服務註冊中心，這些微服務之間的通訊

建立服務提供者

啟動上一節 Eureka入門——叢集的服務內容，把hello-service作為服務提供者，通過java -jar hello.jar --server.port=8181和java -jar hello.jar --server.port=8282啟動兩個hello-service服務，開啟Eureka資訊面板可以看到兩個HELLO-SERVICE例項

建立服務消費者

新建Spring Boot專案MeetSpringCloud

<dependency>
    <groupid>org.springframework.cloud</groupid>
    <artifactid>spring-cloud-starter-ribbon</artifactid>
</dependency>

修改主類MeetSpringCloud.java如下

@EnableDiscoveryClient
@SpringBootApplication
 

public class MeetSpringCloudApplication {
    @Bean
    @LoadBalanced
    RestTemplate restTemplate(){
        return new RestTemplate();
    }

    public static void main(String[] args) {
        SpringApplication.run(MeetSpringCloudApplication.class, args);
    }
}

在包com.centerm.controller下建立類ConsumerController.java

@RestController
@RequestMapping("")
public class ConsumerController {
    @Autowired
    RestTemplate restTemplate;

    @GetMapping("ribbon-consumer")
    public String helloConsumer() {
        return restTemplate.getForEntity("http://HELLO-SERVICE/getIndex",
                String.class).getBody();
    }
}

修改application.yml如下：

server:
  port: 9091
eureka:
  client:
    serviceUrl:
      defaultZone: http://peer1:11111/eureka/,http://peer2:22222/eureka/
spring:
  application:
    name: ribbon-consumer

執行程式，開啟Eureka資訊面板

體驗消費結果

檢視ribbon-consumer的日誌可以看到下面的資訊，列出了可用服務的列表以及訪問狀態等資訊，有關Ribbon的詳細介紹會在後面的章節中涉及

DynamicServerListLoadBalancer for client HELLO-SERVICE initialized: DynamicServerListLoadBalancer:{NFLoadBalancer:name=HELLO-SERVICE,current list of Servers=[AGOD21-05021513:8181, AGOD21-05021513:8282],Load balancer stats=Zone stats: {defaultzone=[Zone:defaultzone;   Instance count:2;   Active connections count: 0;    Circuit breaker tripped count: 0;   Active connections per server: 0.0;]
},Server stats: [[Server:AGOD21-05021513:8282;  Zone:defaultZone;   Total Requests:0;   Successive connection failure:0;    Total blackout seconds:0;   Last connection made:Thu Jan 01 08:00:00 CST 1970;  First connection made: Thu Jan 01 08:00:00 CST 1970;    Active Connections:0;   total failure count in last (1000) msecs:0; average resp time:0.0;  90 percentile resp time:0.0;    95 percentile resp time:0.0;    min resp time:0.0;  max resp time:0.0;  stddev resp time:0.0]
, [Server:AGOD21-05021513:8181; Zone:defaultZone;   Total Requests:0;   Successive connection failure:0;    Total blackout seconds:0;   Last connection made:Thu Jan 01 08:00:00 CST 1970;  First connection made: Thu Jan 01 08:00:00 CST 1970;    Active Connections:0;   total failure count in last (1000) msecs:0; average resp time:0.0;  90 percentile resp time:0.0;    95 percentile resp time:0.0;    min resp time:0.0;  max resp time:0.0;  stddev resp time:0.0]
]}ServerList:org.springf[email protected]1c0a0a56