[Spring cloud 一步步实现广告系统] 19. 监控Hystrix Dashboard

@FeignClient(value = "mscx-ad-sponsor", fallback = SponsorClientHystrix.class)
public interface ISponsorFeignClient {
    @RequestMapping(value = "/ad-sponsor/plan/get", method = RequestMethod.POST)
    CommonResponse<List<AdPlanVO>> getAdPlansUseFeign(@RequestBody AdPlanGetRequestVO requestVO);

    @RequestMapping(value = "/ad-sponsor/user/get", method = RequestMethod.GET)
    /**
     * Feign 埋坑之 如果是Get请求，必须在所有参数前添加{@link RequestParam},不能使用{@link Param}
     * 会被自动转发为POST请求。
     */
    CommonResponse getUsers(@RequestParam(value = "username") String username);
}

@Component
public class SponsorClientHystrix implements ISponsorFeignClient {
    @Override
    public CommonResponse<List<AdPlanVO>> getAdPlansUseFeign(AdPlanGetRequestVO requestVO) {
        return new CommonResponse<>(-1, "mscx-ad-sponsor feign & hystrix get plan error.");
    }

    @Override
    public CommonResponse getUsers(String username) {
        return new CommonResponse<>(-1, "mscx-ad-sponsor feign & hystrix get user error.");
    }
}

@RestController
@Slf4j
@RequestMapping(path = "/search-feign")
public class SearchFeignController {

    /**
     * 注入我们自定义的FeignClient
     */
    private final ISponsorFeignClient sponsorFeignClient;
    @Autowired
    public SearchFeignController(ISponsorFeignClient sponsorFeignClient) {
        this.sponsorFeignClient = sponsorFeignClient;
    }

    @GetMapping(path = "/user/get")
    public CommonResponse getUsers(@Param(value = "username") String username) {
        log.info("ad-search::getUsersFeign -> {}", JSON.toJSONString(username));
        CommonResponse commonResponse = sponsorFeignClient.getUsers(username);
        return commonResponse;
    }
}

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface HystrixCommand {
    ...

        /**
     * Specifies a method to process fallback logic.
     * A fallback method should be defined in the same class where is HystrixCommand.
     * Also a fallback method should have same signature to a method which was invoked as hystrix command.
     * for example:
     * <code>
     *      @HystrixCommand(fallbackMethod = "getByIdFallback")
     *      public String getById(String id) {...}
     *
     *      private String getByIdFallback(String id) {...}
     * </code>
     * Also a fallback method can be annotated with {@link HystrixCommand}
     * <p/>
     * default => see {@link com.netflix.hystrix.contrib.javanica.command.GenericCommand#getFallback()}
     *
     * @return method name
     */
    String fallbackMethod() default "";

    ...
}

@Service
@Slf4j
public class SearchImpl implements ISearch {

    /**
     * 查询广告容错方法
     *
     * @param e 第二个参数可以不指定，如果需要跟踪错误，就指定上
     * @return 返回一个空map 对象
     */
    public SearchResponse fetchAdsFallback(SearchRequest request, Throwable e) {

        System.out.println("查询广告失败，进入容错降级 : %s" + e.getMessage());
        return new SearchResponse().builder().adSlotRelationAds(Collections.emptyMap()).build();
    }

    @HystrixCommand(fallbackMethod = "fetchAdsFallback")
    @Override
    public SearchResponse fetchAds(SearchRequest request) {
        ...
    }
}