Spring Cloud中Sentinel的两种限流模式介绍

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

@SpringBootApplication
@EnableSentinel
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

@RestController
public class DemoController {
    @GetMapping("/hello")
    @SentinelResource(value = "hello", fallback = "fallback")
    public String hello() {
        return "Hello, World!";
    }
    public String fallback() {
        return "Sorry, the service is busy, please try again later.";
    }
}

// 定义资源关联关系
private static final String RESOURCE_A = "resourceA";
private static final String RESOURCE_B = "resourceB";
private static final String RESOURCE_C = "resourceC";

// 定义流控规则
private static final FlowRule RULE_A = new FlowRule(RESOURCE_A)
    .setCount(10) // 每秒最多处理10个请求
    .setGrade(RuleConstant.FLOW_GRADE_QPS);
private static final FlowRule RULE_B = new FlowRule(RESOURCE_B)
    .setCount(20) // 每秒最多处理20个请求
    .setGrade(RuleConstant.FLOW_GRADE_QPS);
private static final FlowRule RULE_C = new FlowRule(RESOURCE_C)
    .setCount(30) // 每秒最多处理30个请求
    .setGrade(RuleConstant.FLOW_GRADE_QPS);

// 定义资源关联关系
private static final Set<FlowRule> RULES_A = new HashSet<>();
private static final Set<FlowRule> RULES_B = new HashSet<>();
private static final Set<FlowRule> RULES_C = new HashSet<>();
static {
    RULES_A.add(RULE_A);
    RULES_A.add(RULE_B);
    RULES_B.add(RULE_B);
    RULES_C.add(RULE_C);
}

// 注册流控规则
FlowRuleManager.loadRules(RULES_A);
FlowRuleManager.loadRules(RULES_B);
FlowRuleManager.loadRules(RULES_C);

// 定义资源关联关系
DegradeRule degradeRuleA = new DegradeRule(RESOURCE_A)
    .setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT)
    .setCount(5) // 每秒最多处理5个异常
    .setTimeWindow(10); // 统计时间窗口为10秒
DegradeRule degradeRuleB = new DegradeRule(RESOURCE_B)
    .setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT)
    .setCount(10) // 每秒最多处理10个异常
    .setTimeWindow(10); // 统计时间窗口为10秒
DegradeRule degradeRuleC = new DegradeRule(RESOURCE_C)
    .setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT)
    .setCount(15) // 每秒最多处理15个异常
    .setTimeWindow(10); // 统计时间窗口为10秒

// 定义资源关联关系
private static final Set<DegradeRule> DEGRADE_RULES_A = new HashSet<>();
private static final Set<DegradeRule> DEGRADE_RULES_B = new HashSet<>();
private static final Set<DegradeRule> DEGRADE_RULES_C = new HashSet<>();
static {
    DEGRADE_RULES_A.add(degradeRuleA);
    DEGRADE_RULES_A.add(degradeRuleB);
    DEGRADE_RULES_B.add(degradeRuleB);
    DEGRADE_RULES_C.add(degradeRuleC);
}

// 注册降级规则
DegradeRuleManager.loadRules(DEGRADE_RULES_A);
DegradeRuleManager.loadRules(DEGRADE_RULES_B);
DegradeRuleManager.loadRules(DEGRADE_RULES_C);