private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {
    if (instances.isEmpty()) {
        if (log.isWarnEnabled()) {
            log.warn("No servers available for service: " + this.serviceId);
        }

        return new EmptyResponse();
    } else if (instances.size() == 1) {
        return new DefaultResponse((ServiceInstance)instances.get(0));
    } else {
        // 輪詢策略的關(guān)鍵代碼
        int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;
        ServiceInstance instance = (ServiceInstance)instances.get(pos % instances.size());
        return new DefaultResponse(instance);
    }
}

int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;

ServiceInstance instance = (ServiceInstance)
                instances.get(pos % instances.size()); // 進(jìn)行輪詢選擇

public class RandomLoadBalancerConfig {

    // 隨機(jī)的負(fù)載均衡策略
    @Bean
    public ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty("loadbalancer.client.name");
        return new RandomLoadBalancer(
                loadBalancerClientFactory.getLazyProvider(name,
                        ServiceInstanceListSupplier.class), name);
    }
}

@Service
@FeignClient("loadbalancer-service")
// 設(shè)置局部的負(fù)載均衡策略
@LoadBalancerClient(name = "loadbalancer-service",
    configuration = RandomLoadBalancerConfig.class)
public interface UserService {

    @RequestMapping("/user/getname")
    public String getName(@RequestParam("id") Integer id);
}

@SpringBootApplication
@EnableFeignClients  // 開啟 OpenFeign
// 設(shè)置全局的負(fù)載均衡策略
@LoadBalancerClients(defaultConfiguration =
    RandomLoadBalancerConfig.class)
public class ConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }

}

@LoadBalancerClients(defaultConfiguration = NacosLoadBalancerConfig.class)
public class NacosLoadBalancerConfig {
    @Resource
    NacosDiscoveryProperties nacosDiscoveryProperties;

    @Bean
    public ReactorLoadBalancer<ServiceInstance> nacosLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty("loadbalancer.client.name");
        return new NacosLoadBalancer(
                loadBalancerClientFactory.getLazyProvider(name,
                        ServiceInstanceListSupplier.class), name, nacosDiscoveryProperties);
    }
}

@Service
@FeignClient("loadbalancer-service")
// 設(shè)置局部的負(fù)載均衡策略
@LoadBalancerClient(name = "loadbalancer-service",
    configuration = NacosLoadBalancerConfig.class)
public interface UserService {

    @RequestMapping("/user/getname")
    public String getName(@RequestParam("id") Integer id);
}

public class CustomLoadBalancer implements ReactorServiceInstanceLoadBalancer {
    private static final Log log = LogFactory.getLog(CustomLoadBalancer.class);
    private final String serviceId;
    private ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;

    public CustomLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {
        this.serviceId = serviceId;
        this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
    }

    public Mono<Response<ServiceInstance>> choose(Request request) {
        ServiceInstanceListSupplier supplier = (ServiceInstanceListSupplier)this.serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);
        return supplier.get(request).next().map((serviceInstances) -> {
            return this.processInstanceResponse(supplier, serviceInstances);
        });
    }

    private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier, List<ServiceInstance> serviceInstances) {
        Response<ServiceInstance> serviceInstanceResponse = this.getInstanceResponse(serviceInstances);
        if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {
            ((SelectedInstanceCallback)supplier).selectedServiceInstance((ServiceInstance)serviceInstanceResponse.getServer());
        }

        return serviceInstanceResponse;
    }

    private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {
        if (instances.isEmpty()) {
            if (log.isWarnEnabled()) {
                log.warn("No servers available for service: " + this.serviceId);
            }

            return new EmptyResponse();
        } else {
            // 自定義負(fù)載均衡策略
            
            // 獲取 Request 對象
            ServletRequestAttributes attributes = (ServletRequestAttributes)
                    RequestContextHolder.getRequestAttributes();
            HttpServletRequest request = attributes.getRequest();
            String ipAddress = request.getRemoteAddr();
            System.out.println("用戶 IP：" + ipAddress);
            int hash = ipAddress.hashCode();
            // IP 哈希負(fù)載均衡【關(guān)鍵代碼】
            int index = hash % instances.size();
            // 得到服務(wù)實(shí)例的方法
            ServiceInstance instance = (ServiceInstance) instances.get(index);
            return new DefaultResponse(instance);
        }
    }
}

public class CustomLoadBalancerConfig {
    // IP 哈希負(fù)載均衡
    @Bean
    public ReactorLoadBalancer<ServiceInstance> customLoadBalancer(Environment environment, LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty("loadbalancer.client.name");
        return new CustomLoadBalancer(
                loadBalancerClientFactory.getLazyProvider(name,
                        ServiceInstanceListSupplier.class), name);
    }
}

@Service
@FeignClient("loadbalancer-service")
// 設(shè)置局部的負(fù)載均衡策略
@LoadBalancerClient(name = "loadbalancer-service",
    configuration = CustomLoadBalancerConfig.class)
public interface UserService {

    @RequestMapping("/user/getname")
    public String getName(@RequestParam("id") Integer id);
}

@SpringBootApplication
@EnableFeignClients  // 開啟 OpenFeign
// 設(shè)置全局的負(fù)載均衡策略
@LoadBalancerClients(defaultConfiguration =
    CustomLoadBalancerConfig.class)
public class ConsumerApplication {

    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }

}