注册中心

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.1.3.RELEASE</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>org.baozi</groupId>
   <artifactId>demo-eureka-server</artifactId>
   <version>1.0</version>
   <name>demo-eureka-server</name>
   <description>Demo project for Spring Boot</description>

   <properties>
      <java.version>1.8</java.version>
      <spring-cloud.version>Greenwich.RELEASE</spring-cloud.version>
   </properties>

   <dependencies>
      <dependency>
         <groupId>org.springframework.cloud</groupId>
         <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
      </dependency>


      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
   </dependencies>

   <dependencyManagement>
      <dependencies>
         <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
         </dependency>
      </dependencies>
   </dependencyManagement>

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

</project>

application.properties

spring.application.name=eureka-server
server.port=8081

eureka.instance.hostname=localhost
# 不注册自己，因为本身这个就是注册中心
eureka.client.register-with-eureka=false
# 是否从eureka server获取注册信息。这里是单点所以false
eureka.client.fetch-registry=false

启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@EnableEurekaServer
@SpringBootApplication
public class DemoEurekaServerApplication {

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

}

服务提供者

<dependencies>
   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
   </dependency>
   <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
   </dependency>

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
   </dependency>
</dependencies>

application.properties

spring.application.name=eureka-provider
server.port=8082

# 设置与Eureka交互的地址，用来查询和注册服务。使用逗号分隔多个。
eureka.client.service-url.defaultZone=http://localhost:8081/eureka/

启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@EnableDiscoveryClient
// @EnableEurekaClient // 这个也可以
@SpringBootApplication
public class DemoEurekaProviderApplication {

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

}

控制器

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ProviderController {

    @Autowired
    private DiscoveryClient discoveryClient;

    @GetMapping("/provider")
    private String provider() {
        return "Services: " + discoveryClient.getServices();
    }

}

服务消费者

<dependencies>
   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
   </dependency>
   <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
   </dependency>

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
   </dependency>
</dependencies>

application.properties

spring.application.name=eureka-consumer
server.port=8083

eureka.client.service-url.defaultZone=http://localhost:8081/eureka/

启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@EnableDiscoveryClient
@SpringBootApplication
public class DemoEurekaConsumerApplication {

   // 用于发起Rest请求
   @Bean
   public RestTemplate restTemplate() {
      return new RestTemplate();
   }

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

}

控制器

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.LoadBalancerClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.text.MessageFormat;

@RestController
public class ConsumerController {

    // 用于发起Rest请求
    @Autowired
    private RestTemplate restTemplate;
    // 负载均衡
    @Autowired
    private LoadBalancerClient loadBalancerClient;

    @GetMapping("/consumer")
    private String consumer() {
        ServiceInstance serviceInstance = loadBalancerClient.choose("eureka-provider");
        String url = MessageFormat.format("http://{0}:{1}/provider",
                // MessageFormat.format会把int类型插入成8,082, 而不是自动转String"8082"
                // 获取Int类型之后手动转: String.valueOf(serviceInstance.getPort())
                serviceInstance.getHost(), String.valueOf(serviceInstance.getPort()));
        return restTemplate.getForObject(url, String.class);
    }

}

分别启动注册中心，提供者，消费者
访问http://localhost:8081/，看到界面
访问http://localhost:8082/provider : Services: [eureka-provider, eureka-consumer]
访问http://localhost:8083/consumer : Services: [eureka-provider, eureka-consumer]