Sentinel API
Github : WIKI
- Sphu （指明要保护的资源名称）
- Tracer （指明调用来源,异常统计接口）
- ContextUtil（标示进入调用链入口）
- 流控规则(针对来源属性)
@GetMapping("/test-sentinel-api")
public String testSentinelAPI(@RequestParam(required = false) String a) {
String resourceName = "test-sentinel-api";
ContextUtil.enter(resourceName, "user-center-service");
// 定义一个sentinel 保护的资源，名称是test-sentinel-api
Entry entry = null;
try {
entry = SphU.entry(resourceName);
// ...被保护的业务逻辑处理
if (StringUtils.isEmpty(a)) {
// Sentinel 默认只会统计BlockException & BlockException的子类，如果想统计其他异常信息，添加Tracer
throw new IllegalArgumentException("A is not empty.");
}
return a;
// block Exception: 如果被保护的资源被限流或者降级了，就会抛异常出去
} catch (BlockException e) {
log.error("我被限流啦！！{}", e);
return "我被限流啦！！";
} catch (IllegalArgumentException argEx) {
// 统计当前异常发生次数 / 占比
Tracer.trace(argEx);
return "非法参数信息";
} finally {
if (entry != null) {
entry.exit();
}
ContextUtil.exit();
}
}
- 降级规则
@GetMapping("/test-sentinel-api")
public String testSentinelAPI(@RequestParam(required = false) String a) {
// 定义一个sentinel 保护的资源，名称是test-sentinel-api
Entry entry = null;
try {
entry = SphU.entry("test-sentinel-api");
// ...被保护的业务逻辑处理
if (StringUtils.isEmpty(a)) {
// Sentinel 默认只会统计BlockException & BlockException的子类，如果想统计其他异常信息，添加Tracer
throw new IllegalArgumentException("A is not empty.");
}
return a;
// block Exception: 如果被保护的资源被限流或者降级了，就会抛异常出去
} catch (BlockException e) {
log.error("我被限流啦！！{}", e);
return "我被限流啦！！";
} catch (IllegalArgumentException argEx) {
// 统计当前异常发生次数 / 占比
Tracer.trace(argEx);
return "非法参数信息";
} finally {
if (entry != null) {
entry.exit();
}
}
}
Sentinel Annotation
源码：com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect & com.alibaba.csp.sentinel.annotation.aspectj.AbstractSentinelAspectSupport
SentinelResource使用该注解重构上述方法
@GetMapping("/test-sentinel-resource")
@SentinelResource(value = "test-sentinel-api", blockHandler = "blockException", fallback = "fallback")
public String testSentinelResource(@RequestParam(required = false) String a) {
// ...被保护的业务逻辑处理
if (StringUtils.isEmpty(a)) {
// Sentinel 默认只会统计BlockException & BlockException的子类，如果想统计其他异常信息，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 对应《限流规则》";
}
/**
* testSentinelResource fallback method
* {@link SentinelResource} #fallback 在< 1.6的版本中，不能补货BlockException
*/
public String fallback(String a) {
return "fallback 对应《降级规则》";
}
RestTemplate 整合Sentinel
使用 @SentinelRestTemplate.
resttemplate.sentinel.enabled可以开关是否启用该注解。（开发阶段很有意义。）
源码：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来开启
- 编写fallback 类，实现feign client
@Component
public class UserCenterFeignClientFallback implements IUserCenterFeignClient {
@Override
public UserDTO findById(Long userId) {
UserDTO userDTO = new UserDTO();
userDTO.setWxNickname("默认用户");
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("远程调用被限流/降级，{}", cause);
UserDTO userDTO = new UserDTO();
userDTO.setWxNickname("默认用户");
return userDTO;
}
};
}
}
- 应用fallback class
/**
* IUserCenterFeignClient for 定义 user-center feign client
* fallbackFactory 可以拿到异常信息
* fallback 无法拿到异常信息
*
* @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);
}
- 启动应用，设置流控规则，结果展示如下
{
id: 1,
...
wxNickName: "默认用户"
}
源码：org.springframework.cloud.alibaba.sentinel.feign.SentinelFeign