Spring Cloud LoadBalancer--指定负载均衡策略--方法/实例

蔚落 2023-10-02 21:02 8阅读 0赞

原文网址：[Spring Cloud LoadBalancer--指定负载均衡策略--方法/实例\_IT利刃出鞘的博客-CSDN博客][Spring Cloud LoadBalancer--_--_IT_-CSDN]

## 简介 ##

本文介绍Spring Cloud LoadBalancer如何使用某个指定的负载均衡策略。

目标：使用Spring Cloud LoadBalance提供的RandomLoadBalancer作为负载均衡策略。其对应的类为：org.springframework.cloud.loadbalancer.core.RandomLoadBalancer。

## 法1：启动类加@LoadBalancerClients（全局） ##

### 第1步：添加配置类（不要加@Configuration） ###

package com.knife.router4j.example.order.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.core.env.Environment;
     
    public class MyLoadBalancerClientConfiguration {
     
    	@Bean
    	public ReactorLoadBalancer<ServiceInstance> reactorServiceInstanceLoadBalancer(Environment environment,
    																				   LoadBalancerClientFactory loadBalancerClientFactory) {
    		String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
    		return new RandomLoadBalancer(
    				loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
    	}
    }

### 第2步：@LoadBalancerClients导入配置 ###

#### 法1：放到启动类上 ####

package com.knife.router4j.example.order;
    
    import com.knife.common.annotation.CommonApplication;
    import com.knife.router4j.example.order.config.MyLoadBalancerClientConfiguration;
    import org.springframework.boot.SpringApplication;
    import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClient;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients("com.knife.**.api")
    @LoadBalancerClients(defaultConfiguration = {MyLoadBalancerClientConfiguration.class})
    public class OrderApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(OrderApplication.class, args);
        }
    
    }

#### 法2：放到@Configuration类上 ####

package com.knife.router4j.example.order.config;
    
    import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClients;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration(proxyBeanMethods = false)
    @LoadBalancerClients(defaultConfiguration = MyLoadBalancerConfiguration.class)
    public class DefaultLoadBalancerConfiguration {
    }

## 法2：@LoadBalancerClient（局部） ##

### 第1步：添加配置类（不要加@Configuration） ###

### 第2步：在启动类上添加@LoadBalancerClient ###

指定哪个服务（本示例为“storage”）使用新的负载均衡策略：

package com.knife.router4j.example.order;
    
    import com.knife.common.annotation.CommonApplication;
    import com.knife.router4j.example.order.config.MyLoadBalancerClientConfiguration;
    import org.springframework.boot.SpringApplication;
    import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClient;
    
    @SpringBootApplication
    @EnableDiscoveryClient
    @EnableFeignClients("com.knife.**.api")
    @LoadBalancerClient(name = "storage", configuration = MyLoadBalancerClientConfiguration.class)
    public class OrderApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(OrderApplication.class, args);
        }
    
    }

## 错误的方法 ##

### 将负载均衡策略注册为bean ###

这样是不行的。因为这样会导致environment.getProperty(LoadBalancerClientFactory.PROPERTY\_NAME);返回为null，后边调用feign时会失败。

官网也说不能直接用@Configuration注册。见：[这里][Link 1]

package com.knife.router4j.example.order.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;
    
    @Configuration
    public class LoadBalancerClientConfiguration {
    
    	@Bean
    	public ReactorLoadBalancer<ServiceInstance> reactorServiceInstanceLoadBalancer(Environment environment,
    																				   LoadBalancerClientFactory loadBalancerClientFactory) {
    		String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
    		return new RandomLoadBalancer(
    				loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class), name);
    	}
    }

[Spring Cloud LoadBalancer--_--_IT_-CSDN]: https://knife.blog.csdn.net/article/details/126823676
[Link 1]: https://docs.spring.io/spring-cloud-commons/docs/current/reference/html/#switching-between-the-load-balancing-algorithms