一 介绍 

从版本1.2.0开始，Spring Cloud支持使用属性来自定义Ribbon客户端。

这种方式比使用Java代码配置的方式更方便。

支持的属性如下，应以<clientName>.ribbon.为前缀：

NFLoadBalancerClassName：应配置ILoadBalancer

NFLoadBalancerRuleClassName：应配置IRule

NFLoadBalancerPingClassName：应配置IPing

NIWSServerListClassName：应配置ServerList

NIWSServerListFilterClassName应配置ServerListFilter

二 ConsumerMovieApplication代码

package com.itmuch.cloud.study;

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

@EnableDiscoveryClient
@SpringBootApplication
public class ConsumerMovieApplication {
  @Bean
  @LoadBalanced
  public RestTemplate restTemplate() {
    return new RestTemplate();
  }

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

三 MovieController代码

package com.itmuch.cloud.study.user.controller;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.itmuch.cloud.study.user.entity.User;

@RestController
public class MovieController {
  private static final Logger LOGGER = LoggerFactory.getLogger(MovieController.class);
  @Autowired
  private RestTemplate restTemplate;
  @Autowired
  private LoadBalancerClient loadBalancerClient;

  @GetMapping("/user/{id}")
  public User findById(@PathVariable Long id) {
    return this.restTemplate.getForObject("http://microservice-provider-user/" + id, User.class);
  }

  @GetMapping("/log-user-instance")
  public void logUserInstance() {
    ServiceInstance serviceInstance = this.loadBalancerClient.choose("microservice-provider-user");
    // 打印当前选择的是哪个节点
    MovieController.LOGGER.info("{}:{}:{}", serviceInstance.getServiceId(), serviceInstance.getHost(), serviceInstance.getPort());
  }
}

四 application.yml配置

server:
  port: 8010
spring:
  application:
    name: microservice-consumer-movie
eureka:
  client:
    serviceUrl:
      defaultZone:http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true
microservice-provider-user:
  ribbon:
    NFLoadBalancerRuleClassName:com.netflix.loadbalancer.RandomRule

五 测试

1 启动eureka

2 启动两user微服务

3 启动movie微服务

4 多次访问 http://localhost:8010/log-user-instance，查看日志，会发现此时请求是随机分布到两个用户微服务节点上。