SpringCloud Ribbon 自定義負載均衡算法

程式結構：

pom.xml 依賴檔案

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.zyu</groupId>
    <artifactId>consumer_service</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>consumer_service</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <!--SpringCloud所有依賴管理的坐标-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>

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

</project>      

方式一

在springboot主程式掃描的包外定義配置類，然後為springboot主程式添加 @RibbonClient 注解引入配置類。

Springboot 主程式：

package com.zyu;

import com.ribbonconfig.MySelfRule;
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.cloud.netflix.ribbon.RibbonClient;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;


@SpringBootApplication
//該注解表明應用既作為eureka執行個體又為eureka client 可以發現注冊的服務
@EnableDiscoveryClient
//在啟動該微服務的時候就能去加載我們的自定義Ribbon配置類，進而使配置生效
@RibbonClient(value = "user-service", configuration = {MySelfRule.class})
public class ConsumerServiceApplication {

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

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

Rule配置檔案類，配置類不應該在SpringBoot的包路徑下，通過@RibbonClient 注解加載：

package com.ribbonconfig;

import com.netflix.loadbalancer.IRule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
public class MySelfRule {
    @Bean
    public IRule getIRule() {
        /**
         * 修改Ribbon 負載均衡政策
         */
        //return new RandomRule();   //預設輪詢，自定義為随機

        /**
         * 自定義 Ribbon 負載均衡政策
         */
        return new MyRule();
    }
}      

自定義LoadBalance：

package com.ribbonconfig;

import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.*;

import java.util.List;
import java.util.Random;


public class MyRule extends AbstractLoadBalancerRule  {

    /**
     * 服務選擇算法，随機調用
     * @param lb
     * @param o
     * @return
     */
    public Server choose(ILoadBalancer lb, Object o) {
        // 擷取伺服器清單
        List<Server> servers = lb.getAllServers();
        // 生産随機數
        Random r = new Random();
        int rand = r.nextInt(10);
        System.out.println("随機數： " + rand);
        if(rand > 7){
            return getServerByPort(servers, 9091);
        } else if (rand > 3) {
            return getServerByPort(servers, 9092);
        }else{
            return getServerByPort(servers, 9093);
        }
    }

    /**
     * 根據傳入的端口号，傳回服務對象
     * @param servers
     * @param port
     * @return
     */
    private Server getServerByPort(List<Server> servers, int port){
        for(Server s : servers){
            if(s.getPort() == port){
                return s;
            }
        }
        return null;
    }


    @Override
    public void initWithNiwsConfig(IClientConfig iClientConfig) {

    }

    @Override
    public Server choose(Object o) {
        return choose(getLoadBalancer(), o);
    }
}      

方式二

application.yml檔案配置方式

#@RibbonClient(name = "user-service") 與name相同，表示針對該微服務使用自定義負載均衡規則
user-service:
  ribbon:
    NFLoadBalancerRuleClassName: com.ribbonconfig.MyRule      

配置的優先級

配置檔案的優先級 > java代碼的配置方式 > netflix自定義的配置方式