02. Ribbon

02. Ribbon

用于负载均衡

在eureka的基础上修改消费者模块

• 添加依赖

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

  如果引入的eureka-client 就可以不用引入ribbon依赖

          <dependency>
              <groupId>org.springframework.cloud</groupId>
              <artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
              <version>2.2.2.RELEASE</version>
          </dependency>
  

• 修改yml

  server:
    port: 8082 #可以设置为80端口, 这样就可以不用输出端口
  spring:
    application:
      name: microsoft-consumer-8082
    thymeleaf:
      cache: false
  eureka:
    client:
      #消费者不用注册仅服务中心,但是从服务中心拿服务fetch-registry 默认开启
      register-with-eureka: false
      service-url:
        #eureka集群
        defaultZone: http://eureka7001.com:7001/eureka/,http://eureka7002.com:7002/eureka/,http://eureka7003.com:7003/eureka/
  
  

• 修改主启动类

  @EnableEurekaClient
  @SpringBootApplication
  public class MicrosoftConsumer8082Application {
  
  	public static void main(String[] args) {
  		SpringApplication.run(MicrosoftConsumer8082Application.class, args);
  	}
  }
  

• 修改ConfigBean

  默认使用ZoneAvoidanceRule类似于RoundRobbin

      @Bean
      //负载均衡
      @LoadBalanced
      public RestTemplate getRestTemplate(){
          return new RestTemplate();
      }
  

• 修改controller

  private static final String REST_URL_PREFIX = "http://microsoft-provider-8081/provider";
  

  如果不需要自定义Ribbon配置运行即可

#自定义Ribbon配置

• The CustomConfiguration class must be a @Configuration class, but take care that it is not in a @ComponentScan for the main application context. Otherwise, it is shared by all the @RibbonClients.

• The following table shows the beans that Spring Cloud Netflix provides by default for Ribbon:

  Bean Type	Bean Name	Class Name
  IClientConfig	ribbonClientConfig	DefaultClientConfigImpl
  IRule	ribbonRule	ZoneAvoidanceRule
  IPing	ribbonPing	DummyPing
  ServerList	ribbonServerList	ConfigurationBasedServerList
  ServerListFilter	ribbonServerListFilter	ZonePreferenceServerListFilter
  ILoadBalancer	ribbonLoadBalancer	ZoneAwareLoadBalancer
  ServerListUpdater	ribbonServerListUpdater	PollingServerListUpdater

  需要将自定义的RibbonConfig放在著启动类扫描范围之外

  #RibbonConfig

  @Configuration(proxyBeanMethods = false)
  public class MyRibbonConfig {
  
      @Bean
      public IRule ribbonRule() {
          return new MyRibbonRule();
      }
  }
  

  #RibbonRule

  //实现随机调用每台服务器五次
  //自定义rule
  public class MyRibbonRule extends AbstractLoadBalancerRule {
      int currentIndex = 0;
      int total = 0;
  
      public Server choose(ILoadBalancer lb, Object key) {
          if (null == lb) {
              return null;
          }
          Server server = null;
          //多线程判断while
          while (server == null) {
              if (Thread.interrupted()) {//检测当前线程是否被打断
                  return null;
              }
              List<Server> upServers = lb.getReachableServers();//当前存活的服务
              List<Server> allServers = lb.getAllServers();//获取所有服务
              int serverCount = allServers.size();
              if (0 == serverCount) {
                  return null;
              }
              if (total < 5) {
                  server = upServers.get(currentIndex);
                  total++;
              } else {
                  total = 0;
                  currentIndex++;
                  if (currentIndex >= upServers.size()) {
                      currentIndex = 0;
                  }
              }
              if (server == null) {
                  /*
                   * The only time this should happen is if the server list were
                   * somehow trimmed. This is a transient condition. Retry after
                   * yielding.
                   */
                  Thread.yield();
                  continue;
              }
              if (server.isAlive()) {
                  return (server);
              }
              // Shouldn't actually happen.. but must be transient or a bug.
              server = null;
              Thread.yield();
          }
          return server;
  
      }
  
  
  
      @Override
      public Server choose(Object key) {
          return choose(getLoadBalancer(), key);
      }
  
      @Override
      public void initWithNiwsConfig(IClientConfig clientConfig) {
  
      }
  }
  

  #主启动类

  //自定义ribbon rule , 如果采用默认的rule不用配置也行
  //name是微服务的名字, 应该采用全大写
  @RibbonClient(name = "MICROSOFT-PROVIDER",configuration = MyRibbonConfig.class)
  @EnableEurekaClient
  @SpringBootApplication
  public class MicrosoftConsumer80Application {
  
  	public static void main(String[] args) {
  		SpringApplication.run(MicrosoftConsumer80Application.class, args);
  	}
  }