SpringCloud 進階之Ribbon和Feign(負載均衡)

1. Ribbon 負載均衡

• Spring Cloud Ribbon是基於Netflix Ribbon實現的一套客戶端,負載均衡的工具;

1.1 Ribbon 配置初步

1.1.1 修改 microservicecloud-consumer-dept-80

// pom.xml
<!-- Ribbon相關 -->
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-ribbon</artifactId>
</dependency>
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-config</artifactId>
</dependency>


// 修改application.yml,追加eureka的服務注冊地址
eureka:
  client:
    register-with-eureka: false
    service-url:
      defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/


// ConfigBean 添加新注解 @LoadBalanced, 用於加入 Ribbon 配置
@Configuration
public class ConfigBean {
	@Bean
	@LoadBalanced
	public RestTemplate getRestTemplate() {
		return new RestTemplate();
	}
}


// 主啟動類 DeptConsumer80_App添加 @EnableEurekaClient
@SpringBootApplication
@EnableEurekaClient
public class DeptConsumer80_App {

	public static void main(String[] args) {

		SpringApplication.run(DeptConsumer80_App.class, args);
	}

}


// 修改 DeptController_Consumer 客戶端訪問類
private static final String REST_URL_PREFIX = "http://MICROSERVICECLOUD-DEPT";


// 測試訪問:
// http://localhost:8082/consumer/dept/get/1
// http://localhost:8082/consumer/dept/list
// http://localhsot:8082/consumer/dept/add?dname=廣告部

1.2 Ribbon 負載均衡

// 新建microservicecloud-provider-dept-8002
// 新建microservicecloud-provider-dept-8003

// 新建8002/8003數據庫

// 修改8002/8003各自YML

1.3 Ribbon 核心組件IRule

• 根據特定算法,從服務列表中選取一個要訪問的服務;
  • RoundRobinRule:輪詢
  • RandomRule:隨機
  • AvailabilityFilteringRule: 會先過濾掉由於多次訪問故障而處於斷路器跳閘狀態的服務,以及並發的連接數量
    超過閾值的服務,然后對剩余的服務列表按照輪詢策略進行訪問;
  • WeightedResponseTimeRule: 根據平均響應時間計算所有服務的權重,響應時間越快,服務權重越大,被選中的機率越高;
    剛啟動時,如果統計信息不足,則使用RoundRobinRule策略,等統計信息足夠時,會切換到WeightedResponseTimeRule
  • RetryRule: 先按照RoundRobinRule的策略獲取服務,如果獲取服務失敗,則在指定時間內會進行重試,獲取可用的服務;
  • BestAvailableRule: 會先過濾掉由於多次訪問故障而處於斷路器跳閘狀態的服務,然后選擇一個並發量最小的服務;
  • ZoneAvoidanceRule: 默認規則,復合判斷server所在區域的性能和server的可用性選擇服務器;

// 修改 microservicecloud-consumer-dept-80
// ConfigBean
@Configuration
public class ConfigBean {

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

	@Bean
	public IRule myRule() {
		return new RoundRobinRule(); // 顯式的指定使用輪詢算法
	}
}

1.4 自定義Ribbon的負載均衡策略

// 修改主啟動類
@SpringBootApplication
@EnableEurekaClient
@RibbonClient(name="MICROSERVICECLOUD-DEPT", configuration=MySelfRule.class)  // 自定義Ribbon配置類
public class DeptConsumer80_App {

	public static void main(String[] args) {

		SpringApplication.run(DeptConsumer80_App.class, args);
	}

}


// com.noodles.myrule
// 自定義Robbin規則類
@Configuration
public class MySelfRule{
    @Bean
    public IRule myRule(){
        return new RandomRule(); //自定義均衡策略
    }
}

2. Feign 負載均衡

• Feign 是一個聲明式WebService客戶端:
  • 使用方法:定義一個接口,然后在上面添加注解;

2.1 創建microservicecloud-consumer-dept-feign

// 參考 microservicecloud-consumer-dept-80

// pom.xml
<!-- Feign相關 -->
<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>


// 修改 microservicecloud-api 工程
    // pom.xml
    <!-- Feign相關 -->
    <dependency>
    	<groupId>org.springframework.cloud</groupId>
    	<artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>


    // 新建DeptClientService接口,並新增注解@FeignClient
    @FeignClient(value="MICROSERVICECLOUD-DEPT")
    public interface DeptClientService {

    	@RequestMapping(value="/dept/get/{id}", method= RequestMethod.GET)
    	public Dept get(@PathVariable("id") long id);

    	@RequestMapping(value="/dept/list", method= RequestMethod.GET)
    	public List<Dept> list();

    	@RequestMapping(value="/dept/add", method= RequestMethod.POST)
    	public boolean add(Dept dept);
    }

    // mvn clean
    // mvn install


// microservice-consumer-dept-feign 工程修改Controller
@RestController
public class DeptController_Consumer {

	@Autowired
	private DeptClientService service;

	@RequestMapping(value="/consumer/dept/get/{id}")
	public Dept get(@PathVariable("id") Long id) {
		return this.service.get(id);
	}

	@RequestMapping(value="/consumer/dept/list")
	public List<Dept> list(){
		return this.service.list();
	}

	@RequestMapping(value="/consumer/dept/add")
	public Object add(Dept dept) {
		return this.service.add(dept);
	}
}


// 修改主啟動類
@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients(basePackages = {"com.noodles.springcloud"})
@ComponentScan("com.noodles.springcloud")
public class DeptConsumer80_Feign_App {

	public static void main(String[] args) {

		SpringApplication.run(DeptConsumer80_Feign_App.class, args);
	}

}

參考資料:

• SpringCloud 教程