[Spring-Cloud-Alibaba] Sentinel 整合RestTemplate & Feign

時間 2019-11-09

標籤 spring cloud alibaba sentinel 整合 resttemplate feign 欄目 Spring 简体版

原文原文鏈接

Sentinel API

Github : WIKI java

Sphu （指明要保護的資源名稱）git
Tracer （指明調用來源,異常統計接口）github
ContextUtil（標示進入調用鏈入口）spring

流控規則(針對來源屬性)json

@GetMapping("/test-sentinel-api")
    public String testSentinelAPI(@RequestParam(required = false) String a) {
        String resourceName = "test-sentinel-api";

        ContextUtil.enter(resourceName, "user-center-service");
        // 定義一個sentinel 保護的資源，名稱是test-sentinel-api
        Entry entry = null;
        try {

            entry = SphU.entry(resourceName);
            // ...被保護的業務邏輯處理
            if (StringUtils.isEmpty(a)) {
                // Sentinel 默認只會統計BlockException & BlockException的子類，若是想統計其餘異常信息，添加Tracer
                throw new IllegalArgumentException("A is not empty.");
            }
            return a;
            // block Exception: 若是被保護的資源被限流或者降級了，就會拋異常出去
        } catch (BlockException e) {
            log.error("我被限流啦！！{}", e);
            return "我被限流啦！！";
        } catch (IllegalArgumentException argEx) {
            // 統計當前異常發生次數 / 佔比
            Tracer.trace(argEx);
            return "非法參數信息";
        } finally {
            if (entry != null) {
                entry.exit();
            }
            ContextUtil.exit();
        }
    }

降級規則api

@GetMapping("/test-sentinel-api")
    public String testSentinelAPI(@RequestParam(required = false) String a) {

        // 定義一個sentinel 保護的資源，名稱是test-sentinel-api
        Entry entry = null;
        try {
            entry = SphU.entry("test-sentinel-api");
            // ...被保護的業務邏輯處理
            if (StringUtils.isEmpty(a)) {
                // Sentinel 默認只會統計BlockException & BlockException的子類，若是想統計其餘異常信息，添加Tracer
                throw new IllegalArgumentException("A is not empty.");
            }
            return a;
            // block Exception: 若是被保護的資源被限流或者降級了，就會拋異常出去
        } catch (BlockException e) {
            log.error("我被限流啦！！{}", e);
            return "我被限流啦！！";
        } catch (IllegalArgumentException argEx) {
            // 統計當前異常發生次數 / 佔比
            Tracer.trace(argEx);
            return "非法參數信息";
        } finally {
            if (entry != null) {
                entry.exit();
            }
        }

    }

Sentinel Annotation

源碼：com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect & com.alibaba.csp.sentinel.annotation.aspectj.AbstractSentinelAspectSupportapp

SentinelResource 使用該註解重構上述方法ide

@GetMapping("/test-sentinel-resource")
    @SentinelResource(value = "test-sentinel-api", blockHandler = "blockException", fallback = "fallback")
    public String testSentinelResource(@RequestParam(required = false) String a) {
        // ...被保護的業務邏輯處理
        if (StringUtils.isEmpty(a)) {
            // Sentinel 默認只會統計BlockException & BlockException的子類，若是想統計其餘異常信息，添加Tracer
            throw new IllegalArgumentException("A is not empty.");
        }
        return a;
    }

    /**
     * testSentinelResource BlockException method
     */
    public String blockException(String a, BlockException e) {
        log.error("限流了,{}", e);
        return "blockHandler 對應《限流規則》";
    }

    /**
     * testSentinelResource fallback method
     * {@link SentinelResource} #fallback 在< 1.6的版本中，不能補貨BlockException
     */
    public String fallback(String a) {
        return "fallback 對應《降級規則》";
    }

RestTemplate 整合Sentinel

使用 @SentinelRestTemplate.ui

resttemplate.sentinel.enabled能夠開關是否啓用該註解。（開發階段頗有意義。）rest

源碼：com.springframework.cloud.alibaba.sentinel.custom.SentinelBeanPostProcessor

@Bean
@LoadBalanced
@SentinelRestTemplate
public RestTemplate restTemplate() {
    return new RestTemplate();
}

@Autowired
private RestTemplate restTemplate;
...

Feign整合 Sentinel

配置文件中添加 feign.sentinel.enabled: true來開啓

編寫fallback 類，實現feign client

@Component
public class UserCenterFeignClientFallback implements IUserCenterFeignClient {
    @Override
    public UserDTO findById(Long userId) {
        UserDTO userDTO = new UserDTO();
        userDTO.setWxNickname("默認用戶");
        return userDTO;
    }
}

@Slf4j
@Component
public class UserCenterFeignClientFallbackFactory implements FallbackFactory<IUserCenterFeignClient> {

    @Override
    public IUserCenterFeignClient create(Throwable cause) {
        return new IUserCenterFeignClient() {
            @Override
            public UserDTO findById(Long userId) {
                log.warn("遠程調用被限流/降級，{}", cause);
                UserDTO userDTO = new UserDTO();
                userDTO.setWxNickname("默認用戶");
                return userDTO;
            }
        };
    }
}

應用fallback class

/**
 * IUserCenterFeignClient for 定義 user-center feign client
 * fallbackFactory 能夠拿到異常信息
 * fallback 沒法拿到異常信息
 *
 * @author <a href="mailto:magicianisaac@gmail.com">Isaac.Zhang | 若初</a>
 * @since 2019/7/15
 */
@FeignClient(name = "user-center",
        // fallback = UserCenterFeignClientFallback.class,
        fallbackFactory = UserCenterFeignClientFallbackFactory.class
)
public interface IUserCenterFeignClient {
    @GetMapping(path = "/users/{userId}")
    public UserDTO findById(@PathVariable Long userId);
}