负载均衡

第一步：引入ribbon依赖

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

第二步：在启动类上加注解（@LoadBalanced）

package cn.itcast;

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 ConsumerApplication {

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

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

第三步：将请求路径改为用户服务的id

package cn.itcast.consumer.web;

import cn.itcast.consumer.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;


@RestController
@RequestMapping("consumer")
public class ConsumerController {

    @Autowired
    private RestTemplate restTemplate;

    @GetMapping("/{id}")
    public User queryUserById(@PathVariable("id") Long id) {

        String url = "http://user-service/user/"+id;
        return this.restTemplate.getForObject(url, User.class);
    }
}

PS：可以在配置文件中修改负载均衡的方法（默认是轮询）

user-service:
  ribbon:
    NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule