出自图灵学院4

代码地址

https://gitee.com/zjj19941/ZJJ_Neaten5.10/tree/master/ZJJ_Sentinel/spring-cloud-alibaba-sentinel-ribbon-feign

详细步骤

Sentinel 适配了 Feign 组件。如果想使用，除了引入 spring-cloud-starter-alibaba-sentinel 的依赖外还需要 2 个步骤：
配置文件打开 Sentinel 对 Feign 的支持：feign.sentinel.enabled=true

  1. feign:
  2.   sentinel:
  3.     enabled: true   #开启sentinel对feign的支持 默认false

加入 spring-cloud-starter-openfeign 依赖使 Sentinel starter 中的自动化配置类生效：

<!-- openfeign 远程调用 -->
<dependency>
  <groupId>org.springframework.cloud</groupId>
  <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<!--sentinel -->
<dependency>
  <groupId>com.alibaba.cloud</groupId>
  <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

在Feign的声明式接口上添加fallback属性 

@FeignClient(value = "mall-order",path = "/order",fallback = FallbackOrderFeignService .class)
public interface OrderFeignService {

    @RequestMapping("/findOrderByUserId/{userId}")
    public R findOrderByUserId(@PathVariable("userId") Integer userId);

}

@Component   //必须交给spring 管理
public class FallbackOrderFeignService implements OrderFeignService {
    @Override
    public R findOrderByUserId(Integer userId) {
        return R.error(-1,"=======服务降级了========");
    }
}

添加fallbackFactory属性

@Component
public class FallbackOrderFeignServiceFactory implements FallbackFactory<OrderFeignService> {
    @Override
    public OrderFeignService create(Throwable throwable) {

        return new OrderFeignService() {
            @Override
            public R findOrderByUserId(Integer userId) {
                return R.error(-1,"=======服务降级了========");
            }
        };
    }
}

UserController

@Autowired
OrderFeignService orderFeignService;

@RequestMapping(value = "/findOrderByUserId/{id}")
public R  findOrderByUserId(@PathVariable("id") Integer id) {
    //feign调用
    R result = orderFeignService.findOrderByUserId(id);
    return result;
}

注意：主启动类上加上@EnableFeignClients注解，开启Feign支持


@SpringBootApplication
@EnableFeignClients
@EnableDiscoveryClient
public class MallUserSentinelRibbonDemoApplication {

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

}

测试
关闭mall-order服务，访问http://localhost:8801/user/findOrderByUserId/4自动降级了

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