参考：http://www.idouba.net/netflix-source-ribbon-rule/?utm_source=tuicool&utm_medium=referral

Spring Cloud还可以通过使用@RibbonClient声明其他配置（在RibbonClientConfiguration之上）来完全控制客户端。 例：

/**
 * 自定义Ribbon的负载均衡
 *
 */
@Configuration
public class RibbonConfig {

    @Autowired
    IClientConfig config;

    @Bean
    @ConditionalOnMissingBean
    public IRule ribbonRule(IClientConfig config) {
        System.out.println("随机的。。。。");
        return new RandomRule();
    }

}

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name = "springcloud-userservcie", configuration = RibbonConfig.class)
public class SpringCloudUserClientApplication {

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

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

@RibbonClient(name = "springcloud-userservcie", configuration = RibbonConfig.class)

注意:RibbonConfig，应该在主启动类之外定义，避免被扫描到，例如：

@RibbonClient，对name为(springcloud-userservcie)的服务端做RibbonConfig.java类中自定义的负载均衡策略。