Spring Cloud微学习（三）Eureka应用——服务间通讯

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/ErErFei/article/details/79075717

微服务可以在“自己的程序”中运行，并通过“轻量级设备与HTTP型API进行沟通”。这里的沟通就是本节要说的服务间通讯。即各个微服务注册到Eureka服务注册中心，这些微服务之间的通讯

创建服务提供者

启动上一节 Eureka入门——集群的服务内容，把hello-service作为服务提供者，通过java -jar hello.jar --server.port=8181和java -jar hello.jar --server.port=8282启动两个hello-service服务，打开Eureka信息面板可以看到两个HELLO-SERVICE实例

创建服务消费者

新建Spring Boot项目MeetSpringCloud，spring.application.name=ribbon-consumer（别怀疑为什么叫ribbon）在pom.xml中增加ribbon依赖

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

修改主类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下创建类ConsumerController.java如下，消费HELLO-SERVICE提供的getIndex服务

@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

运行程序，打开Eureka信息面板

体验消费结果

查看ribbon-consumer的日志可以看到下面的信息，列出了可用服务的列表以及访问状态等信息，有关Ribbon的详细介绍会在后面的章节中涉及

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.springframework.cloud.netflix.ribbon.eureka.DomainExtractingServerList@1c0a0a56