<dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-core</artifactId>
            <version>1.8.9</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-parameter-flow-control</artifactId>
            <version>1.8.9</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-annotation-aspectj</artifactId>
            <version>1.8.9</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-transport-simple-http</artifactId>
            <version>1.8.9</version>
        </dependency>

@Configuration
public class SentinelConfig {
    @PostConstruct
    public void initFlowRules(){
        List<FlowRule> rules = new ArrayList<>();
        FlowRule rule = new FlowRule();
        rule.setResource("HelloWorld");
        rule.setGrade(RuleConstant.FLOW_GRADE_QPS);
        // Set limit QPS to 20.
        rule.setCount(10);
        rules.add(rule);
        FlowRuleManager.loadRules(rules);
    }
    @PostConstruct
    public void initDegradeRules() {
        List<DegradeRule> rules = new ArrayList<>();
        DegradeRule rule = new DegradeRule();
        rule.setResource("HelloWorld");
        rule.setGrade(RuleConstant.DEGRADE_GRADE_RT); // RT threshold degrade strategy
        rule.setCount(200); // Max response time (ms)
        rule.setTimeWindow(10); // Recovery timeout period in seconds
        rules.add(rule);
        DegradeRuleManager.loadRules(rules);
    }
    @Bean
    public SentinelResourceAspect sentinelResourceAspect() {
        return new SentinelResourceAspect();
    }
}

@Service
public class HelloWorldService {
    @SentinelResource(value = "HelloWorld",
        entryType = EntryType.IN,
        exceptionsToIgnore = {IllegalStateException.class},
        blockHandler = "handleBlock",
        fallback = "handleFallback")
    public String sayHello(String name) {
        return "Hello, " + name;
    }
    public String handleBlock(String name, BlockException ex) {
        return "Request blocked by Sentinel: " + ex.getClass().getSimpleName();
    }
    public String handleFallback(String name, Throwable t) {
        return "Request failed and handled by fallback: " + t.getClass().getSimpleName();
    }
}

@RestController
@RequestMapping("/api")
@Tag(name = "登錄接口")
public class HelloWorldController {
    @Autowired
    private HelloWorldService helloWorldService;
    @GetMapping("/hello")
    @Operation(summary = "hello")
    public String sayHello(@RequestParam(value = "name", defaultValue = "World") String name) {
        return helloWorldService.sayHello(name);
    }
}

@SpringBootTest
@Slf4j
public class SentinelTest {
    @Autowired
    HelloWorldService helloWorldService;
    private AtomicInteger successCount = new AtomicInteger(0);
    private AtomicInteger blockCount = new AtomicInteger(0);
    private AtomicInteger fallbackCount = new AtomicInteger(0);
    @BeforeEach
    public void setUp() throws Exception {
        // Reset counters before each test
        successCount.set(0);
        blockCount.set(0);
        fallbackCount.set(0);
    }
    @Test
    public void testRateLimitingAndDegradation() throws InterruptedException {
        log.info("準(zhǔn)備測(cè)試...............");
        TimeUnit.SECONDS.sleep(5);
        log.info("開(kāi)始測(cè)試...............");
        int numberOfThreads = 30; // Number of concurrent threads
        ExecutorService executorService = Executors.newFixedThreadPool(numberOfThreads);
        CountDownLatch latch = new CountDownLatch(numberOfThreads);
        for (int i = 0; i < numberOfThreads; i++) {
            executorService.submit(() -> {
                try {
                    String result = helloWorldService.sayHello("TestUser");
                    if (result.contains("blocked")) {
                        blockCount.incrementAndGet();
                    } else if (result.contains("failed")) {
                        fallbackCount.incrementAndGet();
                    } else {
                        successCount.incrementAndGet();
                    }
                } catch (Exception ex) {
                    System.out.println(ex.getMessage());
                    fallbackCount.incrementAndGet();
                } finally {
                    latch.countDown();
                }
            });
        }
        latch.await(); // Wait until all threads have completed
        log.info("Success count: " + successCount.get());
        log.info("Blocked count: " + blockCount.get());
        log.info("Fallback count: " + fallbackCount.get());
        // Assuming the flow rule is set to allow up to 20 requests per second
        assert successCount.get() <= 20 : "Number of successful requests should not exceed 20";
        assert blockCount.get() > 0 : "Some requests should be blocked due to rate limiting";
        assert fallbackCount.get() == 0 : "No requests should go to fallback under normal conditions";
        executorService.shutdown();
    }
}

java -Dserver.port=8858 -Dcsp.sentinel.dashboard.server=localhost:8858 -Dproject.name=sentinel-dashboard -Dsentinel.dashboard.auth.username=sentinel -Dsentinel.dashboard.auth.password=123456  -Dserver.servlet.session.timeout=7200 -jar sentinel-dashboard-1.8.9.jar

-Dcsp.sentinel.dashboard.server=localhost:8858