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

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

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）

  

   

    

     

    
    

     

      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：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

  

   

    

     

    
    

     

      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);
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     

      }