springcloud之ribbon初识篇-通过代码实现负载均衡

ゞ浴缸里的玫瑰 2023-07-15 01:47 34阅读 0赞

我们在代码中可以使用两种注解实现负载均衡：

*  @RibbonClients：配置所有服务的负载均衡
 *  @RibbonClient：配置单个服务的负载均衡

**@RibbonClients**

@SpringBootApplication
    //给每个服务指定不同的负载规则【PS：“name”指的是要调用的服务名称】
    @RibbonClients(value = {
            @RibbonClient(name = "test1",configuration = RibbonConfiguration.class),
            @RibbonClient(name = "ribbon-java",configuration = RibbonConfiguration2.class)
    })
    public class TestDemoApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(TestDemoApplication.class, args);
        }
    
    }
    
    -----------------------------------------------------------
    @SpringBootApplication
    //调用所有服务时使用统一的负载规则
    @RibbonClients(defaultConfiguration = RibbonConfiguration.class)
    public class TestDemoApplication {
    
        public static void main(String[] args) {
            SpringApplication.run(TestDemoApplication.class, args);
        }
    
    }

**@RibbonClient**

我们可以单独写一个类用来定义某个服务的负载规则，也可以和@RibbonClients联合使用【联合使用看上面代码】

import com.example.springcloud.testdemo.ribbonConfig.RibbonConfiguration2;
    import org.springframework.cloud.netflix.ribbon.RibbonClient;
    import org.springframework.context.annotation.Configuration;
    
    
    @Configuration
    //指定test2使用RibbonConfiguration中定义的负载均衡策略
    @RibbonClient(name = "test1",configuration = RibbonConfiguration.class)
    public class CustomerRibbonConfiguration2 {
    }

**上述两种配置中我们使用的负载均衡配置类是自定义的，用默认的RibbonClientConfiguration调用时无法找到服务实例，暂时不知道是为什么。**

**RibbonConfiguration**：

//@Configuration
    //PS:如果加上了这个配置那么项目加载扫描的时候就会扫描到这个类，会让所有服务都使用这个规则
    public class RibbonConfiguration {
    
        @Bean
        public IRule ribbonRule(){
            return new MyRule();
        }
    }

具体的负载均衡策略：MyRule

import com.netflix.client.config.IClientConfig;
    import com.netflix.loadbalancer.AbstractLoadBalancerRule;
    import com.netflix.loadbalancer.ILoadBalancer;
    import com.netflix.loadbalancer.Server;
    
    import java.util.List;
    
    /**
     * 2020/3/11
     */
    public class MyRule extends AbstractLoadBalancerRule {
        public MyRule() {
            super();
        }
    
        public Server choose(ILoadBalancer lb, Object key){
            if (lb == null) {
                return null;
            }
            Server server = null;
    
            while (server == null) {
                if (Thread.interrupted()) {
                    return null;
                }
                List<Server> upList = lb.getReachableServers();  //激活可用的服务
                List<Server> allList = lb.getAllServers();  //所有的服务
    
                int serverCount = allList.size();
                if (serverCount == 0) {
                    return null;
                }
                //选自定义元数据的server，选择端口以2结尾的服务。
                for (int i = 0; i < upList.size(); i++) {
                    server = upList.get(i);
                    String port = server.getHostPort();
                    if(port.endsWith("2") || port.endsWith("0")) {
                        break;
                    }
    
                }
    
    
                if (server == null) {
                    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 void setLoadBalancer(ILoadBalancer lb) {
            super.setLoadBalancer(lb);
        }
    
        @Override
        public ILoadBalancer getLoadBalancer() {
            return super.getLoadBalancer();
        }
    
        @Override
        public Server choose(Object o) {
            return choose(getLoadBalancer(),o);
        }
    
        @Override
        public void initWithNiwsConfig(IClientConfig iClientConfig) {
    
        }
    }

调用代码：

@Configuration
    public class RibbonComponent {
    
        @Bean
        @LoadBalanced
        public RestTemplate restTemplate(){
            return new RestTemplate();
        }
    
    }
    
    --------------------------------------------------------------
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    import java.util.HashMap;
    import java.util.Map;
    
    
    @RestController
    public class RibbonTest1Controller {
        @Autowired
        private RestTemplate restTemplate;
    
        @RequestMapping("/ribbon/test1")
        public String queryTestRestTemplate(){
            String url = "http://test1/eureka-clinet1/ribbonTest";
            Map<String,String> map = new HashMap<String,String>(){
       {
                put("name","ribboon-test");
            }};
    
            ResponseEntity<String> result =restTemplate.postForEntity(url,map,String.class);
            System.err.println(result.getBody());
            return result.getBody();
        }
    }