SpringBoot中实现限流和熔断功能

原创

JQ实验室

发布于 2025-07-30 14:28:57

7870

我们将使用Java的ScheduledExecutorService来实现一个简单的令牌桶算法（Token Bucket Algorithm），并结合一个自定义的服务类来处理第三方API调用。

1. 创建限流器

首先，创建一个简单的限流器类：

import java.util.concurrent.*;

public class SimpleRateLimiter {
    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
    private Semaphore semaphore;
    private final int permits;
    private final long refillTimeMs;

    public SimpleRateLimiter(int permits, long refillTimeMs) {
        this.permits = permits;
        this.refillTimeMs = refillTimeMs;
        semaphore = new Semaphore(permits);
        scheduleRefill();
    }

    private void scheduleRefill() {
        scheduler.scheduleAtFixedRate(() -> {
            semaphore.release(permits - semaphore.availablePermits());
        }, refillTimeMs, refillTimeMs, TimeUnit.MILLISECONDS);
    }

    public boolean tryAcquire() {
        return semaphore.tryAcquire();
    }
}

这个限流器每refillTimeMs毫秒会补充一定数量的许可（permits），从而控制请求速率。

2. 创建服务类

接下来，创建一个服务类来模拟对第三方API的调用，并集成限流器：

import org.springframework.stereotype.Service;

@Service
public class ThirdPartyService {

    private final SimpleRateLimiter rateLimiter;

    public ThirdPartyService() {
        // 每分钟最多10次请求
        this.rateLimiter = new SimpleRateLimiter(10, 60_000);
    }

    public String fetchData() {
        if (rateLimiter.tryAcquire()) {
            // 模拟调用第三方API
            return "Data from third-party API";
        } else {
            return "Rate limit exceeded, please try again later.";
        }
    }
}

3. 控制器中调用服务

最后，在你的控制器中调用这个服务：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ThirdPartyController {

    @Autowired
    private ThirdPartyService thirdPartyService;

    @GetMapping("/fetchData")
    public String fetchData() {
        return thirdPartyService.fetchData();
    }
}

手动实现熔断器

为了实现简单的熔断器逻辑，我们可以维护一个状态变量来跟踪失败次数，并根据一定的条件决定是否触发熔断。

1. 修改服务类以支持熔断

修改之前的ThirdPartyService类，增加熔断逻辑：

import org.springframework.stereotype.Service;

@Service
public class ThirdPartyService {

    private final SimpleRateLimiter rateLimiter;
    private volatile boolean circuitOpen = false;
    private int failureCount = 0;
    private static final int FAILURE_THRESHOLD = 5; // 失败阈值
    private static final long CIRCUIT_OPEN_TIME_MS = 10_000; // 熔断打开时间

    public ThirdPartyService() {
        this.rateLimiter = new SimpleRateLimiter(10, 60_000);
    }

    public String fetchData() {
        if (circuitOpen) {
            return "Circuit is open, fallback response.";
        }

        if (!rateLimiter.tryAcquire()) {
            return "Rate limit exceeded, please try again later.";
        }

        try {
            // 模拟调用第三方API可能会抛出异常
            if (Math.random() > 0.8) {
                throw new RuntimeException("Third-party service is down");
            }
            resetFailureCount();
            return "Data from third-party API";
        } catch (Exception e) {
            incrementFailureCount();
            return handleFailure(e);
        }
    }

    private void incrementFailureCount() {
        failureCount++;
        if (failureCount >= FAILURE_THRESHOLD) {
            openCircuit();
        }
    }

    private void resetFailureCount() {
        failureCount = 0;
    }

    private void openCircuit() {
        circuitOpen = true;
        new Thread(() -> {
            try {
                Thread.sleep(CIRCUIT_OPEN_TIME_MS);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
            circuitOpen = false;
        }).start();
    }

    private String handleFailure(Exception e) {
        return "Fallback data due to service unavailability: " + e.getMessage();
    }
}

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腾讯技术创作特训营S14#新手村

SpringBoot中实现限流和熔断功能

SpringBoot中实现限流和熔断功能

1. 创建限流器

2. 创建服务类

3. 控制器中调用服务

手动实现熔断器

1. 修改服务类以支持熔断

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