假设是OrderService里面拉取Eureka的服务之一User Service

1.依然需要在该服务里面引入依赖

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

2.在OrderService里面需要有如下配置

spring:
  application:
    name: orderservice #添加的微服务的服务名称,把名字为userservice的微服务加入到注册名单中
eureka:
  client:
    service-url:
      defaultZone: http://localhost:10086/eureka   #eureka的地址信息

3.修改URL和OrderService中添加@Load Balanced注解

1.修改URL

package cn.itcast.eureka.order.service;

import cn.itcast.eureka.order.mapper.OrderMapper;
import cn.itcast.eureka.order.pojo.Order;
import cn.itcast.eureka.order.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@Service
public class OrderService {

    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private RestTemplate restTemplate;
    public Order queryOrderById(Long orderId) {

        // 1.查询订单
        Order order = orderMapper.findById(orderId);
        String url = "http://userservice/user/" + order.getUserId();//OrderService里面拉取Eureka的服务之一User Service
        //把原来的http://localhost:8080/user/变成了http://userservice/user/
        User user = restTemplate.getForObject(url, User.class);
        order.setUser(user);
        // 4.返回
        return order;
    }
}

2.OrderService中添加@Load Balanced注解

package cn.itcast.eureka.order;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@MapperScan("cn.itcast")
@SpringBootApplication
public class OrderApplication {
    @Bean @LoadBalanced
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }

}

通过服务名称获取IP地址的原理如下图所示,其中由于WIndows电脑的设置,原来的IP地址被替换成为了电脑名称LAPTOPXXX,其实还是可以获取到具体的IP