1.在配置文件里进行配置：

spring.cloud.loadbalancer.ribbon.enabled=false

完整的application.properties如下：

server.port=8088
spring.application.name=springboot
spring.datasource.url=jdbc:mysql://139.198.xx.xx/xxx
spring.datasource.username=root
spring.datasource.password=MyPassword
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
eureka.client.serviceUrl.defaultZone=http://139.198.xx.xx:8761/eureka/
eureka.instance.preferIpAddress=true
spring.cloud.loadbalancer.ribbon.enabled=false
spring.cloud.loadbalancer.enabled=true

2.在pom.xml中增加load balancer依赖

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

完整pom.xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.edu.tju</groupId>
    <artifactId>springcloudloadbalancer</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR12</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>





        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.6</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

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

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.30</version>
        </dependency>





        <!-- https://mvnrepository.com/artifact/org.springframework.cloud/spring-cloud-starter-netflix-eureka-client -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            <version>2.1.0.RELEASE</version>


        </dependency>




    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

3.配置RestTemplate

package cn.edu.tju.config;

import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class RestConfig {
    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();

    }
}

4.创建随机策略配置类：

package cn.edu.tju.config;

import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.loadbalancer.core.RandomLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ReactorLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;


public class LoadBalancerConfig {

    @Bean
    ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment,
                                                            LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new RandomLoadBalancer(loadBalancerClientFactory
                .getLazyProvider(name, ServiceInstanceListSupplier.class),
                name);
    }
}

5.在启动类加注解：

@LoadBalancerClient(name = "demoservice", configuration = LoadBalancerConfig.class)

其中name属性为调用的微服务的名称，configuration属性为上一步定义的随机负载均衡策略类
6.创建控制器类，通过RestTemplate来调用微服务：

package cn.edu.tju.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class TestController {
    @Autowired
    private RestTemplate restTemplate;
    @RequestMapping("/hi")
    public String test(){
        String result="";
        for(int i=0;i<100;i++){
            result=restTemplate.getForObject("http://demoservice/test",String.class);
            System.out.println(result);
        }
        return result;
    }
}

其中demoservice是注册到eureka中的一个微服务
7.访问http://localhost:8088/hi,截图如下，可以看到是随机访问了两个微服务实例