public static void main(String[] args) {
   BCryptPasswordEncoder bCryptPasswordEncoder = new BCryptPasswordEncoder();
   // 生成的密码为：$2a$10$04MGTL.cJNZPpR3rFt/I2.43F.V75NH.5wdK.jngaO9Mc91mfonAO
    System.out.println(bCryptPasswordEncoder.encode("admin"));
}

@SpringBootApplication
@EnableDiscoveryClient  //开启 nacos 的服务发现
public class ProviderApplication {
   public static void main(String[] args) {
       SpringApplication.run(ProviderApplication.class, args);
   }
}

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

@RequestMapping
   public Object getUsers() {
       List<ServiceInstance> list = discoveryClient.getInstances("alibaba-provider");
       String targetUrl = list.stream().map(si -> si.getUri() + "/user").findFirst().get();
       List<String> resultList = restTemplate.getForObject(targetUrl, List.class);
       return resultList;
   }

@Configuration
public class WebConfig {
   @LoadBalanced
   @Bean
   public RestTemplate restTemplate() {
       return new RestTemplate();
   }
}

@Bean
public IRule getRule() {
   return new RandomRule();
}

public class Customize_Rule extends AbstractLoadBalancerRule {
   private static Logger logger = LoggerFactory.getLogger(Customize_Rule.class);
   private int currentIndex = 0; //当前调用的索引
   private int num = 1; //次数
   private int limit = 5;
   /**
    * 初始化工作
    * @param iClientConfig
    */
   @Override
   public void initWithNiwsConfig(IClientConfig iClientConfig) {
   }
   @Override
   public Server choose(Object key) {
       ILoadBalancer balancer = getLoadBalancer();
       return choose(balancer, key);
   }
   private Server choose(ILoadBalancer balancer, Object key) {
       Server server = null;
       while(null == server) {
           //获取所有可用的服务
           List<Server> reachableServers = balancer.getReachableServers();
           if (0 == reachableServers.size()) {
               logger.error("没有可用的服务");
               return null;  //退出 while 循环
           }
           int total = reachableServers.size(); //可用服务的数量
           synchronized (this) {
               /**
                * 有种极端情况，当我们在使用最后一个服务的时候，其他的服务都不可用，可能导致索引越界异常
                */
               if (currentIndex + 1 > total) {
                   currentIndex = 0;
                   server = reachableServers.get(currentIndex);  //获取第一个服务
                   num = 0;
                   num++;
               } else {
                   if(limit == num) {
                       currentIndex++;
                       num = 0;
                       if(currentIndex == total) {
                           currentIndex=0;
                           server = reachableServers.get(currentIndex);  //获取第一个服务
                           num++;
                       }else{
                           server = reachableServers.get(currentIndex);
                           num++;
                       }
                   }else {
                       server = reachableServers.get(currentIndex);
                       num++;
                   }
               }
           }
       }
       return server;
   }
}

@Bean
public IRule getRule() {
   return new Customize_Rule();
}

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

@FeignClient(name="alibaba-provider")
public interface UserService {
   @RequestMapping("/user")
   public List<String> getUsers();
}

@RequestMapping("/edit")
@SentinelResource("edit")   //必须的有
public Object edit(@RequestParam(required = false) String id,
                  @RequestParam(required = false) Integer age) {
   return this.studentService.commons();
}

@Component
public class SentinelOriginParser implements RequestOriginParser {
   @Override
   public String parseOrigin(HttpServletRequest httpServletRequest) {
       String origin = httpServletRequest.getParameter("origin");
       if(StringUtil.isBlank(origin)) {
           throw new IllegalArgumentException("origin parameter must be specified.");
       }
       return origin;
   }
}

@SentinelResource(value="edit", blockHandler="editBlock", fallback = "editFallback")
@RequestMapping("/edit")
public Object edit(@RequestParam(required = false) String id,
                  @RequestParam(required = false) Integer age) throws Exception {
   Thread.sleep(20);
   return this.studentService.commons();
}
// 限流的处理
public Object editBlock(String id, Integer age, BlockException ex) {
   Map<String, Object> map = new HashMap<>();
   map.put("msg", "限流了.");
   return map;
}
//服务降级的处理方法
public Object editFallback(String id, Integer age) {
   Map<String, Object> map = new HashMap<>();
   map.put("msg", "fallback 服务降级了.");
   return map;
}

@FeignClient(name="alibaba-provider", fallback = UserServiceFallback.class)
public interface UserService {
   @RequestMapping("/user")
   public List<String> getUsers();
}
UserServiceFallback 的实现如下：
@Component
public class UserServiceFallback implements UserService {
   @Override
   public List<String> getUsers() {
       return Arrays.asList("服务降级了, 这是降级后返回的信息.");
   }
}

@Component
public class UserServiceFallbackFactory implements FallbackFactory<UserService> {
   private static Logger logger = LoggerFactory.getLogger(UserServiceFallbackFactory.class);
   @Override
   public UserService create(Throwable cause) {
       return new UserService() {
           @Override
           public List<String> getUsers() {
               logger.info(cause.getMessage());
               return Arrays.asList("服务降级的方法");
           }
       };
   }
}