<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- 用于實現(xiàn)令牌桶算法 -->
    <dependency>
        <groupId>com.google.guava</groupId>
        <artifactId>guava</artifactId>
        <version>31.1-jre</version>
    </dependency>
</dependencies>

import com.google.common.util.concurrent.RateLimiter;
import org.springframework.stereotype.Component;
import org.springframework.web.filter.OncePerRequestFilter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
@Component
public class IpRateLimitFilter extends OncePerRequestFilter {
    private static final int MAX_REQUESTS_PER_SECOND = 10; // 每個 IP 每秒最大請求數(shù)
    private final Map<String, RateLimiter> rateLimiters = new HashMap<>();
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        String clientIp = getClientIp(request);
        RateLimiter rateLimiter = rateLimiters.computeIfAbsent(clientIp, k -> RateLimiter.create(MAX_REQUESTS_PER_SECOND));
        if (!rateLimiter.tryAcquire()) {
            response.setStatus(HttpServletResponse.SC_TOO_MANY_REQUESTS);
            response.getWriter().write("Too many requests from this IP.");
            return;
        }
        filterChain.doFilter(request, response);
    }
    private String getClientIp(HttpServletRequest request) {
        String xffHeader = request.getHeader("X-Forwarded-For");
        if (xffHeader == null) {
            return request.getRemoteAddr();
        }
        return xffHeader.split(",")[0];
    }
}

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<IpRateLimitFilter> ipRateLimitFilterRegistration() {
        FilterRegistrationBean<IpRateLimitFilter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new IpRateLimitFilter());
        registration.addUrlPatterns("/*"); // 對所有請求進行限流
        registration.setOrder(1);
        return registration;
    }
}

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class TestController {
    @GetMapping("/test")
    public String test() {
        return "Hello, this is a test API.";
    }
}