41.Sentinel

Feign 整合 Sentinel

依赖

        <!--Feign-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <!--sentinel-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>

application.properties

# Feign 整合 Sentinel
feign.sentinel.enabled=true

UserCenterFeignClient

@FeignClient(
        name = "user-center",
//        fallback = UserCenterFeignClientFallback.class
        fallbackFactory = UserCenterFeignClientFallbackFactory.class
)
public interface UserCenterFeignClient {
    @GetMapping("/users/{id}")
    UserDTO queryById(@PathVariable("id") Integer id);
}

UserCenterFeignClientFallback

# 注意一定要加@Component
@Component
public class UserCenterFeignClientFallback implements UserCenterFeignClient {
    @Override
    public UserDTO queryById(Integer id) {
        UserDTO userDTO = new UserDTO();
        userDTO.setWxNickname("默认用户");
        return userDTO;
    }
}

UserCenterFeignClientFallbackFactory

@Component
@Slf4j
public class UserCenterFeignClientFallbackFactory implements FallbackFactory<UserCenterFeignClient> {
    @Override
    public UserCenterFeignClient create(Throwable throwable) {
        return new UserCenterFeignClient() {
            @Override
            public UserDTO queryById(Integer id) {
                log.warn("远程调用被限流/降级了", throwable);
                UserDTO userDTO = new UserDTO();
                userDTO.setWxNickname("默认用户");
                return userDTO;
            }
        };
    }
}

FallbackFactory 比 Fallback 更强大，可以打印更多异常信息。

源码：

规则持久化

• 拉模式
  
  https://www.imooc.com/article/289402