Ribbon实现客户端负载均衡

什么是Ribbon？

客户端负载均衡组件。

前期准备：

搭建一个Eureka集群和一个注册服务

https://www.cnblogs.com/noneplus/p/11374883.html

• 创建服务提供者msc-provider-5002,msc-provider-5003
• 创建消费者msc-consumer-80

pom依赖

服务提供者msc-provider-5001,msc-provider-5002，msc-provider-5003：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
    </properties>

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

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
<!--        Eureka客户端启动需要依赖web模块-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

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

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

消费者msc-consumer-80:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.7.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Greenwich.SR2</spring-cloud.version>
</properties>

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

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
    <!--        Eureka客户端启动需要依赖web模块-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

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

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

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

服务提供者5001配置

• 主启动类：(提供者并不需要进行注解配置)

• TestController（测试负载均衡）

package zkrun.top.controller;

import org.springframework.web.bind.annotation.*;

@RestController
public class TestController {

    @GetMapping(value = "/info/get")
    public String response()
    {
        return "msc_provider_5001";
    }

}

• application.yaml(基本无修改，对比Eureka配置)

server:
  port: 5001
spring:
  application:
    name: msc-provider  #应用名称
eureka:
  client:
    service-url:
      defaultZone: http://eureka6001.com:6001/eureka/,http://eureka6002.com:6002/eureka/,http://eureka6003.com:6003/eureka/
  instance:
    instance-id: msc-provider-5001
    prefer-ip-address: true     #访问路径可以显示IP地址

复制5001的代码到5002和5003

• 主启动类（修改类名）
• TestController（修改返回值）
• application.yaml（修改端口和instance-id）

大致的效果就是访问不同的端口，有不同的返回值：

消费者msc-consumer-80配置

• RibbonConfig

package zkrun.top.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 RibbonConfig {

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

• Controller_Consumer

package zkrun.top.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 Controller_Consumer {

    private static final String REST_URL_PREFIX = "http://MSC-PROVIDER";

    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping(value = "/consumer/info/get")
    public String request()
    {
        return restTemplate.getForObject(REST_URL_PREFIX + "/info/get", String.class);
    }

}

• yaml

server:
  port: 80

eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka6001.com:6001/eureka/,http://eureka6002.com:6002/eureka/,http://eureka6003.com:6003/eureka/

• 主类（@RibbonClient(name="MSC_PROVIDER")）

package zkrun.top;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.ribbon.RibbonClient;

@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name="MSC_PROVIDER")
public class App_msc_consumer_80
{
    public static void main(String[] args)
    {
        SpringApplication.run(App_msc_consumer_80.class, args);
    }
}

运行测试：

启动Eureka6001，6002，6003

启动Provider5001，5002，5003

启动Consumer80

访问：

http://localhost/consumer/info/get

点击刷新就会有轮询效果：

负载均衡算法切换

在RibbonConfig下添加

@Bean
public IRule myRule()
{
        return new RandomRule();// Ribbon默认是轮询，自定义为随机
        //return new RoundRobinRule();// Ribbon默认是轮询
}

支持的算法：

---

代码参考：https://github.com/Noneplus/JavaDev-Note/tree/master/SpringCloud代码