Feign 组件的 fallback 操作

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Feign 组件的 fallback 操作

开启hystrix 熔断器

application.yml


feign:
hystrix:
   enabled: true

方式一:简单,但无法获取异常信息和异常号

FeignClient类


@FeignClient(value = "eureka-client-express-message", fallback = MessageClientHystrix.class)
public interface MessageClient {
​
   @GetMapping("/express-message/getMessageUnRead/{account}")
   R getMessageUnRead(@PathVariable String account);
​
   @GetMapping("/express-message/test")
   String test();
}
​

Hystrix类:重写方法用于当接口访问异常时,即调用的接口抛出异常时调用对应的重写方法,一般用于容错返回和输出异常


@Slf4j
@Component
public class MessageClientHystrix implements MessageClient {
​
   @Override
   public R getMessageUnRead(String account) {
       return R.failed();
   }
​
   @Override
   public String test() {
       log.error("Hystrix error ! ");
       return "";
   }
}
​

被调用服务的控制器


@RestController
public class TestController {
​
   @GetMapping("/test")
   public String test() {
       throw new RuntimeException("服务端测试异常!");
//        return "test";
   }
}

调用方服务的控制器


@RestController
public class TestController {
​
   @Resource
   MessageClient messageClient;
​
   @GetMapping("/test")
   public String test(){
       return messageClient.test();
   }
}

方式二:用Factory,可以获取异常信息和异常号

MessageFeignFactory类


@Component
public class MessageFeignFactory implements FallbackFactory<MessageClient> {
​
   private final MessageClientHystrix messageClientHystrix;
​
   public MessageFeignFactory(MessageClientHystrix messageClientHystrix) {
       this.messageClientHystrix = messageClientHystrix;
   }
​
   @Override
   public MessageClient create(Throwable throwable) {
       throwable.printStackTrace();
       return messageClientHystrix;
   }
}

修改@FeignClient 注解


@FeignClient(value = "eureka-client-express-message", fallbackFactory = MessageFeignFactory.class)
public interface MessageClient {
​
   @GetMapping("/express-message/getMessageUnRead/{account}")
   R getMessageUnRead(@PathVariable String account);
​
   @GetMapping("/express-message/test")
   String test();
}

其他的不用修改

运行结果

image.png

可以看到抛出的异常有状态号信息等