先看服务提供方的，我们在原来的sentinel实例（参见0.9.0.RELEASE版本的spring cloud alibaba sentinel实例）上加上限流、降级处理，三板斧只需在最后那一斧controller类中做如下修改：
@Slf4j
@RestController
static class TestController { @Autowired
private TestService testService; @GetMapping("/hello")
public String hello() {
return testService.hello();
} @GetMapping("/hey")
public String hey() throws InterruptedException {return testService.hey();
} }
再新增一个service类，我们把@SentinelResource挪到这里，并在注解里指定限流、降级的方法：
import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service; @Slf4j
@Service
public class TestService { @SentinelResource(value = "hello", blockHandler = "helloBlock")
public String hello() {
return "hello";
} public String helloBlock(BlockException ex) {
return "hello block";
} @SentinelResource(value = "hey", fallback = "heyFallback")
public String hey() throws InterruptedException {
Thread.sleep(2000);
return "hey";
} public String heyFallback() {
return "hey fallback";
} }
注意限流、降级方法（helloBlock、heyFallback）都需要与原方法参数、返回类型保持一致（限流参数多一个BlockException）。降级的超时是看@SentinelResource所在方法的，所以睡两秒的逻辑也跟着这个注解走，从之前的controller挪到service来。限流、降级规则和jmeter都同之前配置，我们再用jmeter测试下：