Ribbon方式

创建的eureka-consumer工程，pom.xml在client的基础上添加ribbon依赖:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.1.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</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-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>

    <dependency>
        <!--<groupId>org.springframework.cloud</groupId>-->
        <!--<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>-->
    <</dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Finchley.RC1</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

在启动程序Application中同样添加@EnableDiscoveryClient向服务中心注册，并且注入一个beanrestTemplate;
通过@LoadBalanced注解表明开启负载均衡的功能

@EnableDiscoveryClient
@SpringBootApplication
public class EurekaConsumerApplication {

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

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

写一个测试controller类，注入restTemplate，并在/consumer接口中消费之前注册的服务，url为之前注册的EUREKA-CLIENT,

@RestController
public class CosumerController {

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/consumer")
    public String consumer() {
        String url = "http://EUREKA-CLIENT/disc";
        return restTemplate.getForObject(url, String.class);
    }
}

启动之前创建的服务中心，两个客户端和一个消费端，访问刚才创建的接口http://localhost:2101/consumer,浏览器是两个client服务的交替显示，说明ribbon已经做了负载均衡

Services: [eureka-client, eureka-consumer]:2001  #客户端1
Services: [eureka-client, eureka-consumer]:2002  #客户端2
Services: [eureka-client, eureka-consumer]:2001  #客户端1
Services: [eureka-client, eureka-consumer]:2002  #客户端2
Services: [eureka-client, eureka-consumer]:2001  #客户端1
Services: [eureka-client, eureka-consumer]:2002  #客户端2

此时的结构：

• 一个服务中心eureka-server，端口 1001，
• 两个客户端eureka-client, 端口分别是2001 和2002，
• 一个消费端eureka-consumer, 端口是2101，当访问 eureka-consumer时，因为用ribbon进行了负载均衡，会轮流的调用两个客户端。

Feign方式

在之前eureka-consumer基础上，引入Feign，pom.xml文件依赖：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency> 

启动application添加@EnableFeignClients注解，删除restTemplate,修改后如下:

@EnableFeignClients
@EnableDiscoveryClient
@SpringBootApplication
public class EurekaConsumerApplication {

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

添加一个FeignServerClient抽象类接口，通过@FeignClient("服务名")来指定调用哪个服务，比如调用eureka-client

@FeignClient("eureka-client")
public interface FeignServerClient {

    @GetMapping("/disc")
    String consumer();
} 

ConsumerController删除restTemplate,注入刚才创建的抽象类接口

@RestController
public class CosumerController {

    @Autowired
    FeignServerClient feignServerClient;

    @GetMapping("/consumer")
    public String consumer() {
        return feignServerClient.consumer();
    }
} 

按照Ribbon一样启动启动之前创建的服务中心、客户端和消费端，访问http://localhost:2101/consumer,输出结果和ribbon一样，Feign具有负载均衡